This article compares the social and linguistic factors present in the development of three languages (Afrikaans, African American Vernacular English, and Brazilian Vernacular Portuguese), demonstrating that the balance of native and nonnative speakers of their source languages during their early formation led to semicreoles retaining a substantial amount of the source languages' morphosyntax, but also a significant number of substrate and interlanguage structural features. The article concludes with the proposal of a formal theoretical model identifying the linguistic processes that lead to partial restructuring, showing how the insights gained in the study of one semicreole can cast light in understanding the diachronic development and synchronic structure of another.* I would like to thank the Linguistic Society of Southern Africa for providing a travel grant that enabled me to attend the First International Conference on Linguistics in Southern Africa, held at the University of Cape Town, January 12–14, 2000, where I presented an earlier version of this article. I would also like to thank Paul Roberge for his helpful comments on this paper. Responsibility for any errors, however, remains solely my own.