The purpose of this paper is to investigate the historical development of the verbal complements of Modern causative verbs. The paper takes a particularistic approach and examines syntactic properties of each causative verb individually in both Old and Middle English. The examination shows that those verbs have followed diverse paths of change. Based on this examination, the paper refutes the claims of previous studies and argues that counter to many studies, bare- and to-infinitival complements are not synchronically isomorphic nor are to-infinitival and that-clausal complements. It further argues that diachronically the to-infinitival complement is not a replacement of a bare-infinitive or a that-clause as far as the causative verbs are concerned. Finally, it is argued that there was a different degree of semantic integration across the causative verbs in ME, in which let invokes the greatest semantic integration, less so make and have, and least so do which is therefore no longer used as a causative verb in Modern English.