Several distinct approaches to the locality of movement have emerged within the Minimalist Program, but little attention has been paid to their formal and empirical differences. I examine a range of possible locality constraints on movement that are representative of current approaches. I expose some important formal differences among these alternatives and examine five phenomena, some previously unnoted, that distinguish them empirically. No single approach succeeds in capturing all of the facts that should arguably follow from a theory of locality, but the bulk of the evidence seems to support a theory that defines locality using only simple and independently motivated syntactic objects and relations.