To ensure fairness, it is important to better understand the relationship of language proficiency with the standard procedures of psychometric analysis. This paper examines how equating results are affected by an increase in the proportion of examinees who report that English is not their first language, using the analysis samples for a large-scale reading and mathematics test. The results indicate that equating is not affected much by an increase in the proportion of those examinees. (Contains 9 tables and 6 figures.)