This article describes a detailed theoretical analysis of the reaction between allyl and propargyl. In this analysis, we employ high-level electronic structure calculations to characterize the potential energy surface and various forms of transition-state theory (TST) to calculate microcanonical, J-resolved rate coefficients-conventional TST for isomerizations, and the variable reaction coordinate form of variational TST for the "barrierless" association/dissociation processes. These rate coefficients are used in a time-dependent, multiple-well master equation to determine phenomenological rate coefficients, k(T,p), for various product channels. The analysis indicates that the formation of (cyclic) c-C6H7 and c-C6H8 species is suppressed by elevated pressure. Overall, the results suggest that the formation of these five-membered rings from the reaction is not as important as previously thought. A simplified description of the kinetics of the reaction is discussed, and corresponding rate coefficients are provided.