The debate over the characterization of specific language impairment (SLI) is fundamental to theoretical linguistics and, more broadly, to the whole of cognitive science. It is built directly out of the pervasive question regarding the extent to which language ability is best considered as a domain-specific set of skills or as the outcome of various domain-general processes. Therefore, an examination of this issue in conjunction with bilingual language acquisition, a situation that naturally entangles both linguistic and cognitive systems, is a powerful forum for exploring these basic theoretical questions. Paradis' Keynote Article is a substantial contribution to this enterprise: it provides a thorough review of the literature on bilingualism and SLI, and in so doing, evaluates the evidence in terms of its consistency with the maturational model that follows from the tradition of domain-specific language acquisition and the limited processing capacity (LPC) theory, a more domain-general approach. Her extensive review of the literature shows that both second language (L2) learning and bilingualism produce language proficiency profiles that are not identical to those found in SLI, and therefore support neither approach. In our view, the problem is in the attempt to dichotomize language ability as being controlled by either domain-specific or domain-general factors. A more inclusive approach to language ability, especially regarding bilingualism and L2 learning, would set out different criteria for evaluating language development other than the strictly linguistic features used in Paradis' analyses. Such an analysis may lead to a clearer identification of how these experiences uniquely affect language outcomes.