Introduction

It is now well accepted that most star formation occurs in clustered environments, such as associations, groups and clusters (e.g., Lada & Lada 2003). In addition, it is clear that star formation is greatly enhanced in merging galaxies, making them an excellent place to study the formation of large numbers of young, massive stars—albeit with the disadvantage of having to work with stars at larger distances than the nearby groups and clusters in our own galaxy. In keeping with their galactic counterparts, most of the stars in merging galaxies also form in clusters, the brightest and most compact of which have been dubbed “super star clusters.” Hence, understanding what triggers the formation of star clusters in mergers may be an important clue for understanding the formation of stars in general.