In their Keynote Article, Clahsen and Felser (CF) provide a detailed summary and comparison of grammatical processing in adult first language (L1) speakers, child L1 speakers, and second language (L2) speakers. CF conclude that child and adult L1 processing makes use of a continuous parsing mechanism, and that any differences found in processing can be explained by factors such as limited working memory capacity and incomplete lexical knowledge. The authors then suggest that the existing differences between L1 (both adult and child) and L2 processing provide evidence that parsing mechanisms are qualitatively different between these groups. They posit that this qualitative difference between L1 and L2 is due to L2 speakers having shallower and less detailed syntactic representations than L1 speakers. This commentary focuses on discussing this shallow structures account and considers what this means for L2 processing.