Watching Organic Reactions Single-molecule studies can overcome the difficulty of inferring the various outcomes of reactions in ensemble measurements. De Oteyza et al. (p. 1434 , published online 30 May; see the Perspective by Giessibl ) used a variation of noncontact atomic force microscopy in which the imaging tip was derivatized with a single CO molecule to obtain subnanometer-resolution images of conjugated organic molecules undergoing reaction on a silver surface. Different thermally induced cyclization reactions of oligo- (phenylene-1,2-ethynylenes) were observed.