We are evaluating the question whether the cluster environment plays a significant role in morphologically transforming galaxies, or whether this morphological evolution instead primarily occurs in the group environment prior to cluster assembly. The focus of our program is the supergroup SG1120-1202 (z=0.37), a system that includes four groups that are expected to coalesce into a massive cluster by z=0. Using HST/ACS observations, we compare the morphologies of the supergroup galaxies to that of local and intermediate redshift clusters to study whether the properties of these group galaxies match already those seen in the clusters or if they are yet to be transformed.