diff --git a/TODO b/TODO
index 2f22223..03f876f 100644
--- a/TODO
+++ b/TODO
@@ -1,7 +1,6 @@
 TODO list
 =========
 - manage cross-references
-+ labels
 - find (authors) duplicates
 + remove command
 - stats command
diff --git a/papers/commands/add_cmd.py b/papers/commands/add_cmd.py
index 41d4126..bea1d6c 100644
--- a/papers/commands/add_cmd.py
+++ b/papers/commands/add_cmd.py
@@ -45,7 +45,7 @@ def command(config, ui, bibfile, docfile, label, copy):
     else:
         p = Paper.load(bibfile)
     if label is not None:
-        p.metadata['labels'] = label.split()
+        p.tags = set(label.split())
     # Check if another doc file is specified in bibtex
     docfile2 = extract_doc_path_from_bibdata(p, ui)
     if docfile is None:
diff --git a/papers/commands/list_cmd.py b/papers/commands/list_cmd.py
index 37946d2..57f0e16 100644
--- a/papers/commands/list_cmd.py
+++ b/papers/commands/list_cmd.py
@@ -9,7 +9,7 @@ def parser(subparsers, config):
             default=False, dest='citekeys',
             help='Only returns citekeys of matching papers.')
     parser.add_argument('query', nargs='*',
-            help='Paper query (e.g. "year: 2000" or "labels: math")')
+            help='Paper query (e.g. "year: 2000" or "tags: math")')
     return parser
 
 
@@ -23,12 +23,12 @@ def command(config, ui, citekeys, query):
         paper_strings = []
         for n, p in papers:
             bibdesc = pretty.bib_oneliner(p.bibentry)
-            paper_strings.append((u'{num:d}: [{citekey}] {descr} {labels}'.format(
+            paper_strings.append((u'{num:d}: [{citekey}] {descr} {tags}'.format(
                 num=int(n),
                 citekey=color.dye(p.citekey, color.purple),
                 descr=bibdesc,
-                labels=color.dye(' '.join(p.metadata.get('labels', [])),
-                                 color.purple, bold=True),
+                tags=color.dye(' '.join(p.tags),
+                               color.purple, bold=True),
                 )).encode('utf-8'))
     ui.print_('\n'.join(paper_strings))
 
@@ -45,8 +45,8 @@ def test_paper(query_string, p):
         field = tmp[0]
         value = tmp[1]
 
-        if field in ['labels', 'l', 'tags', 't']:
-            if value not in p.metadata['labels']:
+        if field in ['tags', 't']:
+            if value not in p.tags:
                 return False
         elif field in ['author', 'authors', 'a']:  # that is the very ugly
             if not 'author' in p.bibentry.persons:
diff --git a/papers/commands/tags_cmd.py b/papers/commands/tags_cmd.py
index ce43ee7..c56384d 100644
--- a/papers/commands/tags_cmd.py
+++ b/papers/commands/tags_cmd.py
@@ -9,5 +9,5 @@ def parser(subparsers, config):
 def command(config, ui):
     """List existing tags"""
     rp = Repository.from_directory(config)
-    for tag in rp.get_labels():
+    for tag in rp.get_tags():
         ui.print_(tag)
diff --git a/papers/paper.py b/papers/paper.py
index 2f003e6..55d5705 100644
--- a/papers/paper.py
+++ b/papers/paper.py
@@ -20,7 +20,7 @@ CITEKEY_EXCLUDE_RE = re.compile('[%s]'
 
 BASE_META = {
     'external-document': None,
-    'labels': [],
+    'tags': [],
     'notes': [],
     }
 
@@ -250,7 +250,30 @@ class Paper(object):
             return papers
 
 
-class PaperInRepo(Paper):
+    # tags
+
+    @property
+    def tags(self):
+        return self.metadata.setdefault('tags', set())
+
+    @tags.setter
+    def tags(self, value):
+        if not hasattr(value, '__iter__'):
+            raise ValueError, 'tags must be iterables'
+        self.metadata['tags'] = set(value)
+
+    def add_tag(self, tag):
+        self.tags.add(tag)
+
+    def remove_tag(self, tag):
+        """Remove a tag from a paper. Fails silently."""
+        try:
+            self.tags.pop(tag)
+        except KeyError:
+            pass
+
+
+class PaperInRepo(Paper): # TODO document why this class exists (fabien, 2013/06)
 
     def __init__(self, repo, *args, **kwargs):
         Paper.__init__(self, *args, **kwargs)
diff --git a/papers/repo.py b/papers/repo.py
index 4db7a67..6486890 100644
--- a/papers/repo.py
+++ b/papers/repo.py
@@ -198,11 +198,11 @@ class Repository(object):
             new_doc_file = os.path.join(doc_path, citekey + ext)
             shutil.copy(doc_file, new_doc_file)
 
-    def get_labels(self):
-        labels = set()
+    def get_tags(self):
+        tags = set()
         for p in self.all_papers():
-            labels = labels.union(p.metadata.get('labels', []))
-        return labels
+            tags = tags.union(p.tags)
+        return tags
 
     @classmethod
     def from_directory(cls, config, papersdir=None):
diff --git a/tests/test_paper.py b/tests/test_paper.py
index be99a90..43b37c6 100644
--- a/tests/test_paper.py
+++ b/tests/test_paper.py
@@ -24,7 +24,7 @@ entries:
 META = """
 external-document: null
 notes: []
-labels: []
+tags: []
 """