diff --git a/_conda b/_conda
index 8b6f40e..0d99f59 100644
--- a/_conda
+++ b/_conda
@@ -287,6 +287,8 @@ __conda_commands(){
         list:'List linked packages in a conda environment.'
         remove:'Remove a list of packages from a specified conda environment.'
         uninstall:'Alias for conda remove'
+        activate:'Activate an environment; alias for source activate'
+        deactivate:'Deactivate an environment; alias for source deactivate'
     )
     help=(
         help:'Displays a list of available conda commands and their help strings.'
@@ -609,6 +611,14 @@ case $state in
             ;;
         esac
         ;;
+    (activate)
+            _arguments -C $help_opts \
+                          '--stack[activate this environment on top of the previous environment]' \
+                          '*:environment:__conda_envs'
+                    ;;
+    (deactivate)
+            _arguments -C $help_opts \
+                    ;;
     esac
     ;;
 esac