Research on the economic or labor market assimilation of immigrants has to date focused on the degree of improvement in their economic status with duration in the destination. This pattern has been found for all the immigrant receiving countries, time periods and data sets that have been studied. The theoretical underpinning for this finding is the international transferability of skills. This paper addresses whether positive assimilation will be found if skills are very highly transferable internationally. It outlines the conditions for negative assimilation in the context of the traditional immigration assimilation model, and examines the empirical relevance of the hypothesis using data on immigrants from the English-speaking developed countries (i.e., the UK, Ireland, Canada and Australia/New Zealand) to the United States. Comparisons with the native born are also presented to test whether the findings are sensitive to immigrant cohort quality effects. Even after controlling for cohort effects, negative assimilation (a decline in earnings with duration) is found for immigrants in the US from the English-speaking developed countries.