This paper is about a class of strange attractors that have the dual property of occurring naturally and being amenable to analysis. Roughly speaking, a rank one attractor is an attractor that has some instability in one direction and strong contraction in m−1 directions, m here being the dimension of the phase space. The results of this paper can be summarized as follows. Among all maps with rank one attractors, we identify, inductively, subsets Gn, n = 1, 2, 3, · · · ,