The initial results from HST imaging studies give the impression that SSCs are only found in rather violent settings such as merging and interacting galaxies. The first announcement, for example, was that of the well-known merging and/or cooling-flow galaxy NGC 1275 (Holtzman et al. 1992). Two similar studies of merger systems quickly followed: numerous SSCs were found in the ``Antennae'' system (NGC 4038/NGC 4039; Whitmore et al. 1993) and in the ``Atoms for Peace'' galaxy (NGC 7252; Whitmore & Schweizer 1995). Likewise, Conti and collaborators (Conti & Vacca 1994; Vacca 1994, 1996; Leitherer et al. 1996; Conti, Leitherer, & Vacca 1996) are finding from their ultraviolet (UV) imaging program that SSCs invariably show up in Wolf-Rayet (W-R) galaxies, most of which are known to show signs of interaction. The discovery of luminous, young clusters generated considerable excitement and rekindled interest in the idea that globular clusters might form in galaxy mergers (Burstein 1987; Schweizer 1987; Ashman & Zepf 1992).
While these studies certainly point to a plausible relation between galaxy interaction and the formation of SSCs, one must be careful in drawing any direct, causal connection between the two processes. The cases cited above by no means represent an unbiased sample; in fact, they were, to a large extent, selected based on prior knowledge of their extreme characteristics. It is well known that galaxy interactions can give rise to intense starburst activity (see contributions in Shlosman 1994). Similarly, W-R galaxies are among the earliest and most vigorous manifestations of starbursts (Conti 1991; Vacca & Conti 1992). Thus, an equally viable interpretation is that cluster formation is an integral part of star formation in starbursts in general. In as much as galaxy interactions can trigger starbursts, there is a high likelihood of finding SSCs in interacting systems; but such an association is indirect - interactions are sufficient but not necessary for cluster formation. That SSCs are also found in galaxies that are not obviously interacting (O'Connell et al. 1994; Meurer et al. 1995) supports this viewpoint, as does the tendency for some SSCs to be located in circumnuclear rings and other relatively quiescent environments, as will be described below.