This paper discusses support for, and opposition to, racial classification of European immigrants among high-level researchers at both the United States Immigration Commission of 1907 - 11 (the Dillingham Commission) and the Census Bureau during those same years. A critical distinction must be made between the Commission members - political appointees who mostly supported some form of restriction at the time of their appointment - and the top research staff, whose views were remarkably wide ranging. Moreover, even staff members committed to a racialized outlook - such as Daniel Folkmar, author of the Commission's infamous Dictionary of Races and Peoples - deserve a closer look than historians have given them; for example, Folkmar and his superior on the staff had requested commentary from Franz Boas, who was then emerging as the most prestigious academic critic of racial theories (theories that assume group differences in behavior arise from biological endowments). Another feature of the narrative concerns the surprising number of staff who transferred from the Commission to the Census Bureau to work on the 1910 Census. Debates continued at the Bureau as well, this time over how to present the results of the new mother tongue question, which had been introduced to the Census questionnaire in response to pressure for a European race question. Indeed, Folkmar was also the chief author of the Census Bureau report on the mother-tongue data.