Do I need retention straps with cross-country bindings?

For track skiing on groomed trails at Nordic centers, retention straps are generally unnecessary since the terrain is flat and a released ski is unlikely to run away. For any backcountry or off-trail skiing, especially on slopes, retention straps are strongly recommended to prevent runaway skis after an unexpected release. Some BC bindings include strap attachment points; for others, you may need to add straps separately.