Hanley, Jin, Vanselow, and Hanratty (2014) described a functional analysis (FA) format that relied on a synthesis of multiple contingencies described by caregivers during open-ended interviews. These interview-informed synthesized contingency analyses (IISCA) provided effective baselines from which to develop socially validated treatments, but the synthesis precluded a precise understanding of individual contingencies influencing problem behavior. We conducted IISCAs and standard FAs (Iwata, Dorsey, Slifer, Bauman, & Richman, 1982/1994) for nine children with autism to evaluate the likelihood of differentiation given a number of synthesized versus isolated variables. The IISCA was differentiated for all. The standard FA was differentiated for four; this number increased to six when we included precursors in the standard FA. We then compared treatments based on sets of differentiated analyses for four children. Treatment based on the IISCA was effective for all four; treatments based on the standard FA were effective for two. The role of synthesis in analysis is discussed.