diff --git a/README.md b/README.md
index b19456d..400be37 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,10 @@ Lastly, run with:
 
 You will need a proxy such as nginx to access the forum on the public internet.
 
+## Upgrading
+
+To upgrade from a previous version, run ``upgrade_sqlite.sh``
+
 ## Screenshots
 
 ![Index](https://static.agreper.com/index.png)
diff --git a/db/sqlite.py b/db/sqlite.py
index 0d72f44..dad5562 100644
--- a/db/sqlite.py
+++ b/db/sqlite.py
@@ -19,7 +19,7 @@ class DB:
             on t.thread_id = (
               select tt.thread_id
               from threads tt
-              where f.forum_id = tt.forum_id
+              where f.forum_id = tt.forum_id and not tt.hidden
               order by update_time desc
               limit 1
             )
@@ -35,31 +35,64 @@ class DB:
             (forum_id,)
         ).fetchone()
 
-    def get_threads(self, forum_id, offset, limit):
+    def get_threads(self, forum_id, offset, limit, user_id):
         return self._db().execute('''
-            select t.thread_id, title, t.create_time, t.update_time, t.author_id, name, count(c.thread_id)
-            from threads t, users
-            left join comments c on t.thread_id = c.thread_id
-            where forum_id = ? and user_id = t.author_id
+            select
+              t.thread_id,
+              title,
+              t.create_time,
+              t.update_time,
+              t.author_id,
+              name,
+              count(c.thread_id),
+              t.hidden
+            from
+              threads t,
+              users
+            left join
+              comments c
+            on
+              t.thread_id = c.thread_id
+            where forum_id = ?
+              and user_id = t.author_id
+              and (
+                t.hidden = 0 or (
+                  select 1 from users
+                  where user_id = ?
+                    and (
+                      user_id = t.author_id
+                      -- 1 = moderator, 2 = admin
+                      or role in (1, 2)
+                    )
+                )
+              )
             group by t.thread_id
             order by t.update_time desc
             limit ?
             offset ?
             ''',
-            (forum_id, limit, offset)
+            (forum_id, user_id, limit, offset)
         )
 
     def get_thread(self, thread):
         db = self._db()
-        title, text, author, author_id, create_time, modify_time = db.execute('''
-            select title, text, name, author_id, create_time, modify_time
+        title, text, author, author_id, create_time, modify_time, hidden = db.execute('''
+            select title, text, name, author_id, create_time, modify_time, hidden
             from threads, users
             where thread_id = ? and author_id = user_id
             ''',
             (thread,)
         ).fetchone()
         comments = db.execute('''
-            select comment_id, parent_id, author_id, name, text, create_time, modify_time
+            select
+              comment_id,
+              parent_id,
+              author_id,
+              name,
+              text,
+              create_time,
+              modify_time,
+              hidden
             from comments
               left join users
               on author_id = user_id
@@ -67,7 +100,7 @@ class DB:
             ''',
             (thread,)
         )
-        return title, text, author, author_id, create_time, modify_time, comments
+        return title, text, author, author_id, create_time, modify_time, comments, hidden
 
     def get_thread_title(self, thread_id):
         return self._db().execute('''
@@ -123,8 +156,21 @@ class DB:
                 union
                 select comment_id from descendant_of, comments where id = parent_id
               )
-            select id, parent_id, author_id, name, text, create_time, modify_time from descendant_of, comments, users
-            where id = comment_id and user_id = author_id
+            select
+              id,
+              parent_id,
+              author_id,
+              name,
+              text,
+              create_time,
+              modify_time,
+              hidden
+            from
+              descendant_of,
+              comments,
+              users
+            where id = comment_id
+              and user_id = author_id
             ''',
             (comment_id,)
         )
@@ -475,6 +521,24 @@ class DB:
             (role, user_id)
         )
 
+    def set_thread_hidden(self, thread_id, hide):
+        return self.change_one('''
+            update threads
+            set hidden = ?
+            where thread_id = ?
+            ''',
+            (hide, thread_id)
+        )
+
+    def set_comment_hidden(self, comment_id, hide):
+        return self.change_one('''
+            update comments
+            set hidden = ?
+            where comment_id = ?
+            ''',
+            (hide, comment_id)
+        )
+
     def change_one(self, query, values):
         db = self._db()
         c = db.cursor()
diff --git a/init_sqlite.sh b/init_sqlite.sh
index 6eb1f95..2709ceb 100755
--- a/init_sqlite.sh
+++ b/init_sqlite.sh
@@ -38,7 +38,7 @@ $SQLITE "$1" -init schema.txt "insert into config (
 	registration_enabled
 )
 values (
-	'agreper-v0.1',
+	'agreper-v0.1.1',
 	'Agreper',
 	'',
 	'$(head -c 30 /dev/urandom | base64)',
diff --git a/main.py b/main.py
index 97ac77d..e7d1ed8 100644
--- a/main.py
+++ b/main.py
@@ -1,4 +1,4 @@
-VERSION = 'agreper-v0.1'
+VERSION = 'agreper-v0.1.1'
 # TODO put in config table
 THREADS_PER_PAGE = 50
 
@@ -42,7 +42,8 @@ def index():
 def forum(forum_id):
     title, description = db.get_forum(forum_id)
     offset = int(request.args.get('p', 0))
-    threads = [*db.get_threads(forum_id, offset, THREADS_PER_PAGE + 1)]
+    user_id = session.get('user_id', -1)
+    threads = [*db.get_threads(forum_id, offset, THREADS_PER_PAGE + 1, user_id)]
     if len(threads) == THREADS_PER_PAGE + 1:
         threads.pop()
         next_page = offset + THREADS_PER_PAGE
@@ -62,18 +63,19 @@ def forum(forum_id):
 
 @app.route('/thread/<int:thread_id>/')
 def thread(thread_id):
-    user_id = session.get('user_id')
-    title, text, author, author_id, create_time, modify_time, comments = db.get_thread(thread_id)
-    comments = create_comment_tree(comments)
+    user = get_user()
+    title, text, author, author_id, create_time, modify_time, comments, hidden = db.get_thread(thread_id)
+    comments = create_comment_tree(comments, user)
     return render_template(
         'thread.html',
         title = title,
         config = config,
-        user = get_user(),
+        user = user,
         text = text,
         author = author,
         author_id = author_id,
         thread_id = thread_id,
+        hidden = hidden,
         create_time = create_time,
         modify_time = modify_time,
         comments = comments,
@@ -81,8 +83,9 @@ def thread(thread_id):
 
 @app.route('/comment/<int:comment_id>/')
 def comment(comment_id):
+    user = get_user()
     thread_id, parent_id, title, comments = db.get_subcomments(comment_id)
-    comments = create_comment_tree(comments)
+    comments = create_comment_tree(comments, user)
     reply_comment, = comments
     comments = reply_comment.children
     reply_comment.children = []
@@ -90,7 +93,7 @@ def comment(comment_id):
         'comments.html',
         title = title,
         config = config,
-        user = get_user(),
+        user = user,
         reply_comment = reply_comment,
         comments = comments,
         parent_id = parent_id,
@@ -574,6 +577,42 @@ def admin_restart():
     restart()
     return redirect(url_for('admin'))
 
+@app.route('/thread/<int:thread_id>/hide/', methods = ['POST'])
+def set_hide_thread(thread_id):
+    chk, user = _moderator_check()
+    if not chk:
+        return user
+
+    try:
+        hide = request.form['hide'] != '0'
+        hide_str = 'Hidden' if hide else 'Unhidden'
+        if db.set_thread_hidden(thread_id, hide):
+            flash(f'{hide_str} thread', 'success')
+        else:
+            flash(f'Failed to {hide_str.lower()} thread', 'error')
+    except Exception as e:
+        flash(str(e), 'error')
+
+    return redirect(request.form['redirect'])
+
+@app.route('/comment/<int:comment_id>/hide/', methods = ['POST'])
+def set_hide_comment(comment_id):
+    chk, user = _moderator_check()
+    if not chk:
+        return user
+
+    try:
+        hide = request.form['hide'] != '0'
+        hide_str = 'Hidden' if hide else 'Unhidden'
+        if db.set_comment_hidden(comment_id, hide):
+            flash(f'{hide_str} comment', 'success')
+        else:
+            flash(f'Failed to {hide_str.lower()} comment', 'error')
+    except Exception as e:
+        flash(str(e), 'error')
+
+    return redirect(request.form['redirect'])
+
 # TODO can probably be a static-esque page, maybe?
 @app.route('/help/')
 def help():
@@ -601,7 +640,7 @@ def _admin_check():
 
 
 class Comment:
-    def __init__(self, id, author_id, author, text, create_time, modify_time, parent_id):
+    def __init__(self, id, parent_id, author_id, author, text, create_time, modify_time, hidden):
         self.id = id
         self.author_id = author_id
         self.author = author
@@ -610,23 +649,35 @@ class Comment:
         self.create_time = create_time
         self.modify_time = modify_time
         self.parent_id = parent_id
+        self.hidden = hidden
 
-def create_comment_tree(comments):
+def create_comment_tree(comments, user):
     start = time.time();
     # Collect comments first, then build the tree in case we encounter a child before a parent
-    comment_map = {
-        comment_id: Comment(comment_id, author_id, author, text, create_time, modify_time, parent_id)
-        for comment_id, parent_id, author_id, author, text, create_time, modify_time
-        in comments
-    }
+    comment_map = { v[0]: Comment(*v) for v in comments }
     root = []
+    # We should keep showing hidden comments if the user replied to them, directly or indirectly.
+    # To do that, keep track of user comments, then walk up the tree and insert hidden comments.
+    user_comments = []
     # Build tree
-    for comment in comment_map.values():
+    def insert(comment):
         parent = comment_map.get(comment.parent_id)
         if parent is not None:
             parent.children.append(comment)
         else:
             root.append(comment)
+    for comment in comment_map.values():
+        if comment.hidden and (not user or not user.is_moderator()):
+            continue
+        insert(comment)
+        if user and (comment.author_id == user.id and not user.is_moderator()):
+            user_comments.append(comment)
+    # Insert replied-to hidden comments
+    for c in user_comments:
+        while c is not None:
+            if c.hidden:
+                insert(c)
+            c = comment_map.get(c.parent_id)
     # Sort each comment based on create time
     def sort_time(l):
         l.sort(key=lambda c: c.modify_time, reverse=True)
diff --git a/schema.txt b/schema.txt
index fdd8869..819618e 100644
--- a/schema.txt
+++ b/schema.txt
@@ -27,7 +27,7 @@ create table threads (
 	title        varchar(64)  not null,
 	text         text         not null,
 	score        integer      not null  default 0,
-	dead         boolean      not null  default false
+	hidden       boolean      not null  default false
 );
 
 create table comments (
@@ -39,7 +39,7 @@ create table comments (
 	modify_time  integer      not null,
 	text         text         not null,
 	score        integer      not null  default 0,
-	dead         boolean      not null  default false
+	hidden       boolean      not null  default false
 );
 
 create table forums (
diff --git a/templates/comment.html b/templates/comment.html
index d67ca67..d4b4024 100644
--- a/templates/comment.html
+++ b/templates/comment.html
@@ -1,10 +1,13 @@
+{% from 'moderator.html' import moderate_comment with context -%}
+
 {%- macro author(id, name, ctime, mtime) -%}
 <i><a href="{{ url_for('user_info', user_id = id) }}">{{ name }}</a> - {{ format_since(ctime) }}{% if ctime != mtime %} (last modified {{ format_since(mtime) }}){% endif %}</i>
 {%- endmacro -%}
 
 {%- macro comment_author(comment, thread_id, can_delete) -%}
 <span class=small>
-{{- author(comment.author_id, comment.author, comment.create_time, comment.modify_time) }} |
+{{- '[hidden]' if comment.hidden else '' }}
+{{ author(comment.author_id, comment.author, comment.create_time, comment.modify_time) }} |
 {# Suffixing a # prevents unnecessary reloads #}
 <a href="{{ url_for('thread', thread_id = thread_id) }}#"> thread</a>
 {%- if comment.parent_id is not none -%}
@@ -15,6 +18,9 @@
 {%- if can_delete -%}
 <a href="{{ url_for('confirm_delete_comment', comment_id = comment.id) }}"> delete</a>
 {%- endif -%}
+{%- if user.is_moderator() -%}
+{{ moderate_comment(comment.id, comment.hidden) }}
+{%- endif -%}
 {%- endif -%}
 </span>
 {%- endmacro -%}
diff --git a/templates/forum.html b/templates/forum.html
index 7c4350f..ac7c1f4 100644
--- a/templates/forum.html
+++ b/templates/forum.html
@@ -1,4 +1,5 @@
 {% extends 'base.html' %}
+{%- from 'moderator.html' import moderate_thread with context %}
 
 {%- macro nav() -%}
 <p style=text-align:center>
@@ -19,14 +20,22 @@
 		<th>Created</th>
 		<th>Updated</th>
 		<th>Comments</th>
+		{%- if user is not none and user.is_moderator() -%}
+		<th>Action</th>
+		{%- endif -%}
 	</tr>
-	{% for id, title, ctime, utime, author_id, author, comment_count in threads %}
+	{% for id, title, ctime, utime, author_id, author, comment_count, hidden in threads %}
 	<tr>
-		<th><a href="{{ url_for('thread', thread_id = id) }}">{{ title }}</a></th>
+		<th>{{ '[hidden] ' if hidden else '' }}<a href="{{ url_for('thread', thread_id = id) }}">{{ title }}</a></th>
 		<td><a href="{{ url_for('user_info', user_id = author_id) }}">{{ author }}</a></td>
 		<td>{{ format_since(ctime) }}</td>
 		<td>{{ format_since(utime) }}</td>
 		<td>{{ comment_count }}</td>
+		<td>
+		{%- if user is not none and user.is_moderator() %}
+		{{- moderate_thread(id, hidden) }}
+		{%- endif -%}
+		</td>
 	</tr>
 	{%- endfor -%}
 </table>
diff --git a/templates/moderator.html b/templates/moderator.html
new file mode 100644
index 0000000..d6a0bc8
--- /dev/null
+++ b/templates/moderator.html
@@ -0,0 +1,15 @@
+{% macro moderate_thread(id, hidden) %}
+<form method=post action="{{ url_for('set_hide_thread', thread_id = id) }}">
+<input name=redirect value="{{ request.full_path }}" hidden>
+<input name=hide value={{ 0 if hidden else 1 }} hidden>
+<input type=submit value="{{ 'Unhide' if hidden else 'Hide' }}">
+</form>
+{% endmacro %}
+
+{% macro moderate_comment(id, hidden) %}
+<form method=post action="{{ url_for('set_hide_comment', comment_id = id) }}" style=display:inline>
+<input name=redirect value="{{ request.full_path }}" hidden>
+<input name=hide value={{ 0 if hidden else 1 }} hidden>
+<input type=submit value="{{ 'Unhide' if hidden else 'Hide' }}">
+</form>
+{% endmacro %}
diff --git a/templates/thread.html b/templates/thread.html
index 80a6c62..049a636 100644
--- a/templates/thread.html
+++ b/templates/thread.html
@@ -1,8 +1,12 @@
 {%- extends 'base.html' %}
 {%- from 'comment.html' import render_comment, reply, thread_author with context %}
+{%- from 'moderator.html' import moderate_thread with context %}
 
 {%- block content %}
-{{ thread_author(author_id, author, create_time, modify_time) }}
+{%- if user is not none and user.is_moderator() -%}
+<p>{{ moderate_thread(thread_id, hidden) }}</p>
+{%- endif -%}
+{{- thread_author(author_id, author, create_time, modify_time) }}
 <p>{{ minimd(text) | safe }}</p>
 
 {{- reply() }}
diff --git a/upgrade/sqlite/v0.1.sh b/upgrade/sqlite/v0.1.sh
new file mode 100644
index 0000000..8c1b7f0
--- /dev/null
+++ b/upgrade/sqlite/v0.1.sh
@@ -0,0 +1,9 @@
+set -ex
+test $# == 1
+"$SQLITE" "$1" "
+begin exclusive;
+	alter table threads rename dead to hidden;
+	alter table comments rename dead to hidden;
+	update config set version = 'agreper-v0.1.1';
+end;
+"
diff --git a/upgrade_sqlite.sh b/upgrade_sqlite.sh
new file mode 100755
index 0000000..5837d8a
--- /dev/null
+++ b/upgrade_sqlite.sh
@@ -0,0 +1,86 @@
+#!/usr/bin/env bash
+
+# Script to upgrade a database from one version to another by adding columns,
+# tables etc.
+# Upgrade scripts go into upgrade/sqlite/
+# If there are multiple changes after a revision but before a new one, suffix a
+# letter (e.g. `v0.1.1a`).
+# When a new revision is out, add a script that changes just the version.
+
+LAST_VERSION=agreper-v0.1.1
+
+SQLITE=sqlite3
+
+export SQLITE
+
+set -e
+
+if [ $# -lt 1 ]
+then
+	echo "Usage: $0 <file.db> [--no-backup]" >&2
+	exit 1
+fi
+
+make_backup=0
+
+if [ $# -ge 2 ]
+then
+	case "$2" in
+		--no-backup)
+			make_backup=1
+			;;
+		*)
+			echo "Unknown option $2"
+			exit 1
+			;;
+	esac
+fi
+
+if ! [ -f "$1" ]
+then
+	echo "Database '$1' doesn't exist" >&2
+	exit 1
+fi
+
+version=$(sqlite3 "$1" 'select version from config')
+
+while true
+do
+	case "$version" in 
+		# Last version, do nothing
+		agreper-v0.1.1)
+			echo "$version is the latest version"
+			exit 0
+			;;
+		# Try to upgrade
+		agreper-*)
+			echo "Upgrading from $version"
+
+			if [ $make_backup ]
+			then
+				backup="$1.bak-$version"
+				if [ -f "$backup" ]
+				then
+					echo "Backup '$backup' already exists (did a previous upgrade fail?)" >&2
+					exit 1
+				fi
+				echo "Creating backup of $1 at $backup"
+				cp --reflink=auto "$1" "$backup"
+				make_backup=1
+			fi
+
+			script="./upgrade/sqlite/${version#agreper-}.sh"
+			if ! bash "$script" "$1"
+			then
+				echo "Error while executing $script"
+				exit 1
+			fi
+			;;
+		# Unrecognized version
+		*)
+			echo "Unknown version $version" >&2
+			exit 1
+			;;
+	esac
+	version=$(sqlite3 "$1" 'select version from config')
+done