Abstract The wave function, or form factor, to be used for the captured particle in a stripping reaction is discussed. It is shown that the structure of the nucleus must be taken into account, and leads to a set of coupled equations for this form factor. Approximate solutions to these equations are studied, and their relations to various phenomenological prescriptions for the form factor are discussed. It is stressed that if an effective one-body potential well is used to generate that wave function, it is probably not sufficient merely to vary its depth, but changes in shape (particularly in radius) must be considered. The procedure of using an effective binding energy different from the separation energy is shown, in principle, to be wrong.