This paper discusses the OSCE Parliamentary Assembly (OSCE-PA) as an international parliamentary institution (IPI), briefly recounting its institutional history and establishing the bases for comparing it with other IPIs. Next, the paper sets out the activity of the OSCE's parliamentary diplomacy, through its Parliamentary Assembly, in Central Asia and the South Caucasus. It then sets out the similar activity of other Euro-regional IPIs in order to provide comparative perspective. Subsequently it examines the OSCE-PA's institutional development also in this same comparative perspective. It concludes by taking note of the most recent developments of OSCE-PA's activity in Central Asia and the South Caucasus, and also the most recent developments in Central Asia and the South Caucasus pertinent to that activity. The final remarks include some general considerations about IPIs in the world today, relating them to the OSCE-PA's present, past and potential future activity.