Natural products that contain stereocenters such as those having polyacetate and polypropionate structures are of considerable interest. Current technology for constructing these chiral molecules consists of strategies broadly defined as “acyclic stereocontrol.” The most efficient tools for this strategy include modern aldol reactions and the reaction of carbonyl compounds with allylmetal reagents. In order to achieve highly efficient syntheses of natural products rich with stereochemistry, highly stereoselective transformations are required. One solution is the use of allylstannane reagents. Their advantages include ease of handling, relative stability, and selective reactivity. The addition of allystannanes to aldehydes combines the process of CC bond formation with the stereoselective production of one or two new stereocenters. The configuration of these centers is predictable based on reaction conditions. Oxygen substitution also contributes to the versatility of these reagents. Recently developed chiral allenystannanes and the use of InCl3 as a transmetallation agent have greatly enhanced the practical utility of these reagents. This chapter is limited mainly to carbonyl and imine addition reactions, most of which create one or two new stereocenters.