In this article I discuss the selection and assembly of formal features in second language acquisition. Assembling the particular lexical items of a second language (L2) requires that the learner reconfigure features from the way these are represented in the first language (L1) into new formal configurations on possibly quite different types of lexical items in the L2. I illustrate the nature of the problem by comparing the assembly and expression of features involved in plural-marking in English, Mandarin Chinese and Korean, and situate this comparison with respect to specific claims of the Nominal Mapping Parameter and within a discussion of parameter (re)setting more generally. I conclude with a few even more general thoughts on the role of Universal Grammar (UG) in (second) language acquisition. (Contains 37 footnotes.)