The well-known successive refinement scenario is extended to vector sources where individual distortion constraints are posed on every vector component. This extension is then utilized for the derivation of a necessary and sufficient condition for vector successive refinability. For 2-D vector Gaussian and binary symmetric sources, it turns out that successive refinability is not granted everywhere, unlike in the 1-D case for the same sources. Moreover, the behavior of these sources with respect to successive refinability exhibit remarkable similarity.