The effects of aryl ring substitution on the dynamic resoln. of aryl(methyl)phenylphosphanes under asym. Appel reaction conditions have been studied.  As expected, substitution at the ortho position strongly affects the degree ofstereoselection that can be achieved.  Unexpectedly, however, there was no variation of stereoselectivity with the electronic nature of the para substituents, which suggests that there are two selection processes in operation.  An unusual halogen-exchange process was obsd. in the arylphenylphosphinous chlorides on route to the required tertiary phosphane substrates.