This paper analyzes the grammaticalization of modal verbs in Brazilian Portuguese from a synchronic perspective. It takes as its point of departure the hypothesis that grammaticalization is a process in which linguistic elements widen their scope. Since this process is gradual and involves one step at a time, the synchronic correlate of this hypothesis is that if a modal verb has multiple meanings, these meanings should be of contiguous scope types on the grammaticalization scale in their synchronic distribution. The corpus data on which the paper is based show that this prediction is fully confirmed.