Basic laboratory research has shown that variability is an operant dimension of behavior (Page & Neuringer, 1985). Applied research on behavioral variability has been conducted with a variety of populations and response topographies; however, no research has been conducted with adults with developmental disabilities, and only one study has targeted activity selection (Cammilleri & Hanley, 2005). In the present study, varied activity selection was reinforced according to a Lag 1 schedule of reinforcement. The present study also evaluated whether selection of novel activities occurred in the absence of differential reinforcement and assessed generalization of varied activity selection. Varied activity selection increased for all participants although prompts to select activities were required for 2 of 3 participants. Few novel selections occurred throughout the study and varied activity selection did not generalize to participants' natural environments. These results suggest that a lag schedule of reinforcement can be used to increase varied activity selection by adults with developmental disabilities but should be implemented in the natural environment.