The unimolecular rearrangement and fragmentation mechanisms of several alkyl enolate ions have been investigated using Fourier transform ion cyclotron resonance mass spectrometry and infrared multiple photon activation techniques. We have observed unusual fragmentations induced by infrared multiple activation of several enolate ions that do not follow previously generalized pathways. Two new mechanisms are proposed to explain the unusual fragmentations. First, we propose the intermediacy of an alkyl radical/ketene radical anion complex that is formed by homolytic cleavage. This complex is expected when the alkyl anion is unbound. Within this complex, the alkyl radical can either abstract a hydrogen from the ketene radical anion to form deprotonated ketene anion and an alkane or transfer a hydrogen to the ketene radical anion to form an aldehyde enolate ion and an alkene. Second, we propose that vibrationally activated enolate ions can undergo a 1,3-methyl rearrangement in addition to a 1,3-hydrogen rearrangement. The proposed mechanisms appear to be general and are able to predict the fragmentations of other enolate ions.