Previous research suggests that motivating operation (MO) manipulations may assist in assessing discriminated manding (Gutierrez et al., 2007). The current study partially replicated and extended previous research by varying access to concurrently available reinforcers with different preference values (i.e., MO manipulations). Manding did not occur (a) for reinforcers that were freely available and (b) for lower preference items when relatively higher preference reinforcers were freely available. Results further demonstrated the utility of manipulating MOs to verify discriminated mands but suggest that relative preference of alternative reinforcers should be controlled during these assessments. (Contains 1 figure.)