This study explores complex language in adolescents with specific language impairment (SLI) with the aim of finding out how aspects of language characteristic of typical syntactic development after childhood fare and, in particular, whether there is evidence that individuals with SLI avoid using structures whose syntactic derivation involves greater computational complexity. An analysis of spontaneous language samples of 18 French-speaking adolescents with SLI, compared to groups of typically developing speakers, showed that whereas complexity increases with age in the latter, behaviors of avoidance are clear in the former, in the form of low frequencies of complex structures, but also frequency of failed attempts and alternative strategies. Whereas increasing complexity is the hallmark of syntactic development after childhood, avoidance of complexity appears to characterize SLI after childhood.