Making decisions about residential or day program placement for adults with developmental disabilities requires examination of multidimensional measures of behavior and thus the use of multivariate statistical techniques along with expert opinion. This study used adaptive and maladaptive cluster scores on the Inventory for Client and Agency Planning (ICAP) to examine the multidimensional nature of behavioral characteristics for 1,884 adults with developmental disabilities, identified the variables having the strongest relationship with various residential and/or day programs, and predicted current residential and day program placement. The ICAP consists of seven behavior scales: motor skills, social/communication skills, personal living skills, community living skills, maladaptive behavior, asocial maladaptive behavior, and externalized maladaptive behavior. The study makes the following conclusions: (1) there is statistical support for the residential and day program placement decisions made by consensus building among team members and by expert opinion; (2) errors in prediction based on the multivariate analysis were in favor of the less restrictive environment; (3) adaptive behavior was the theoretical construct best discriminating among adults in residential and day programs; and (4) support is provided for the use of multivariate statistical techniques as a tool in the decision making process. (20 references) (JDD)