Sidman's (2000) theory of stimulus equivalence predicts an interaction between the development of analytic units and the development of equivalence relations. Previous research has documented these interactions (stewart, Barnes-Holmes, Roche, & Smeets, 2002; Vaidya & Brackney, 2014), therefore the current study attempted to replicate the effects seen in Vaidya & Brackney, 2014 (Experiment 2). Baseline conditional discriminations were trained for two sets of three, three-member classes, while participants simply observed stimuli in the third set which was arranged identical to those of Sets 1 and 2. Following equivalence tests where performance met the accuracy criterion of 85% for Sets 1 and 2, participants then entered a simple successive discrimination training phase where common responses were then trained with an equivalence class (pressing the Q key in the presence of A1, B1, or C1), cross equivalence classes (pressing the R key in the presence of A4, A5, or A6), or for stimuli where the participants had experience with them, but the contingencies were never arranged to facilitate equivalence class formation. Results showed a facilitative effect for common responses drawn from within equivalence classes (Set 1), and a retardation effect for common responses drawn from across equivalence classes (Set 2), for three of the five participants. Results for Set 3 showed an acquisition that fell intermediate to that of Sets 1 and 2, respectively, suggesting an interaction occurring between existing equivalence relations and the development of analytic units.