The concept of segmented assimilation is both the most important and most controversial idea to have emerged over the past twenty years from the literature on the children of immigrants in the US. This article traces the origins of the concept, attempts to unravel the controversy surrounding it and to show how the concept has evolved. We consider the major findings from the largest and most widely cited research studies about the children of immigrants in the US. We find that segmented assimilation has been used both simply to describe the diversity of educational and economic outcomes among the children of immigrants and as a typology to explain those outcomes. The typology has been the more controversial use and has undergone several alterations since its introduction. We conclude that the emphasis on national origins in both description and explanation should be replaced with a focus on social contexts and processes.