I review the main issues in the current debate on how and when massive black holes form. I then discuss the implications of the possible black hole formation scenarios for LISA event rates. I conclude by noting that LISA will not only address the problem of massive black hole formation but may also provide important constraints on the overall process of galaxy and large structure formation. The structure we see around us today likely formed hierarchically from the progressive merger of smaller objects. If those smaller objects are like those we see today in that they contain massive black holes with properties that track those of their host objects and if their black holes also merge when they merge (I will show some preliminary calculations that this is indeed the case), then LISA detections provide a powerful tracer of structure formation -- even if LISA helps show that gas accretion and not the merging of black holes is the dominant process for growing the supermassive black holes we find at the centers of present-day galaxies.