This paper compares monolingual acquisition to the acquisition of two languages from infancy. Basis for the comparison is the acquisition literature. Specifically for bilingual acquisition, the paper relies on findings from studies on young bilingual children who together are acquiring 13 languages in 14 different combinations. The data available to date strongly suggest that in essence, bilingual and monolingual children go through the primary language development process in fundamentally similar ways. There are also striking similarities between bilingual and monolingual children for one particular language-in-acquisition. The acquisition process, then, appears to be very robust, and quite immune to the fact whether a child...