Two recent findings are summarized here that bear on the organization of memory and brain systems. First, the capacity for simple recognition of familiarity (a form of declarative memory) depends on the hippocampal region in both humans and nonhuman primates. Second, probabilistic classification learning (a form of nondeclarative memory akin to habit learning) depends on the caudate nucleus and putamen. These findings are related to the classification of long-term memory and current understanding of the participating brain systems.