Children acquiring French elaborate their early verb constructions by adding morphemes incrementally starting at the left edge of core verbs. This hypothesis was tested with 2657 verb uses from four children between 1;3 and 2;7. Consistent with the adjacency hypothesis, children added adjacent morphemes first: clitic subjects to present tense forms (as in il saute ‘he jumps’); modals to infinitives (as in faut sauter ‘has to jump’); and auxiliaries to past participles (as in a sauté ‘has jumped’, est parti ‘has left’). Only after this did the children add clitic subjects to the left of a modal or auxiliary, as in elle veut sauter ‘she wants to jump’, or elle a sauté ‘she has jumped’. The order in which these elements were added in verb constructions supports the predictions of the adjacency hypothesis for the left edge developments in early verb constructions.