This study reports on a comparison of the use and knowledge of tense-marking morphemes in English by first language (L1), second language (L2), and specific language impairment (SLI) children. The objective of our research was to ascertain whether the L2 children's tense acquisition patterns were similar or dissimilar to those of the L1 and SLI groups, and whether they would fit an (extended) optional infinitive profile, or an L2-based profile, for example, the missing surface inflection hypothesis. Results showed that the L2 children had a unique profile compared with their monolingual peers, which was better characterized by the missing surface inflection hypothesis. At the same time, results reinforce the assumption underlying the (extended) optional infinitive profile that internal constraints on the acquisition of tense could be a component of L1 development, with and without SLI.