The article by Amaral and Roeper (this issue; henceforth A&R) presents many interesting ideas about first and second language acquisition as well as some experimental data convincingly illustrating the difference between production and comprehension. The article extends the concept of Universal Bilingualism proposed in Roeper (1999) to second language acquisition. As stated in the Introduction, the idea of Multiple Grammars (MG) is in some sense obvious in the context of second language acquisition. In this commentary, the author focuses on some aspects of the theory that are left somewhat unclear, namely the nature of complexity and the "size" of rules as well as the question of what constitutes conflicting (sub-)grammars. The author also compares the MG theory to her own model of micro-cues (Westergaard, 2009a, 2009b), discussing some similarities and differences, the latter mainly due to the micro-cue model claiming that the rules of early child language are smaller and more specific than has previously been assumed.