Here, mechanistic studies have been employed to advance the hydrogenation of unactivated olefins via cHAT. Demonstration of the compatibility of chiral thiol catalysts with these Fe-catalyzed reactions is a central finding, supported by the first observations of appreciable enantioinduction by iron-based catalysts under mHAT conditions. Kinetic studies of the reaction employing achiral catalysts show that the rate is zero-order with respect to all reagents except silane. Solvolysis studies with PhSi(OiPr)H2 suggest that PhSi(OEt)H2 is faster in the hydrogenation reaction than PhSi(OiPr)H2. These both indicate that formation of the [Fe III ]-H intermediate is the turnover limiting step, and the pseudo-zero order dependence on iron concentration may be explained by the observed catalyst deactivation. From our kinetic studies, spectroscopic work, and computations, we propose a mechanism for cHAT that includes iron(II) thiol binding and transfer of H atom from the ironbound thiol to the alkyl radical for PCET delivery of the second hydrogen atom in the enantiodetermining step. This forms an iron(III)-thiolate intermediate, which was observed by Mössbauer spectroscopy. We used these insights to explore the asymmetric hydrogenation of thiazolidines containing prochiral olefins, employing a commercially available glucose-derived chiral thiol catalyst. The mechanistic exploration of this system guided our choice of nonpolar solvent mixtures, bulkier ligands, and a more reactive silane to ultimately provide enhanced yield and rate, as well as enhanced er in several cases. Exploration of the substrate scope suggests that the degree of enantioinduction is substrate-dependent with a high sensitivity to steric environment, rather than arising from non-covalent interactions.