The word “to” that precedes verbs in English infinitives is optional in at least two environments: in what Wasow et al. (2015) previously called the “do-be” construction, and in the complement of “help”, which we explore in the present work. In the “do-be” construction, Wasow et al. found that a preceding infinitival “to” increases the use of following optional “to”, but the use of “to” in the complement of help is reduced following “to help”. We examine two hypotheses regarding why the same function word is primed by prior use in one construction and inhibited in another. We then test predictions made by the two hypotheses, finding support for one of them.