Photolysis of indene oxides is well known to produce isochromenes via rearrangement and vice-versa. The hitherto accepted mechanism supposes photolytic cleavage of the oxirane to give a 1,3-diradical. Subsequent β-cleavage gives a ground-state dienal which readily and rapidly cyclizes to an isochromene. The reverse process has been believed to begin with photo induced retro-cyclization to an excited dienal which rearranges to a ground-state version of the 1,3-diradical which readily closes to give the indene oxide. Our work with the photolysis of substituted indene-oxides forces us to put forth a substantially different mechanism in which both processes proceed through a common point: a conical intersection. Experimental and computational results will be presented to illustrate our proposal.