The results of the recent International Biological Program and other studies suggest that nutrients, especially nitrogen, may limit productivity in desert ecosystems when moisture is available. Few studies examined decomposition processes in desert ecosystems prior to the initiation of our work, but here were fairly extensive efforts focused on nitrogen processes in desert ecosystems as part of the International Biological Program. In this review, I will address the problem of both decomposition and nutrient cycling processes in desert ecosystems and attempt, wherever possible, to demonstrate the relationships between these processes and primary productivity. Since these processes are mediated via the soil biota, I will emphasize soil biotic interactions and their importance, where these are known or suspected.