The Immigration Restriction League (IRL) made literacy, and by extension education, a major aspect of immigration reform in United States in the early twentieth century. Appealing to an educated, conservative constituency, it promoted a literacy test aimed at systematically excluding "undesirable" immigrants. Literacy was initially treated as a learned skill, but eventually became linked to fixed, presumably heritable traits. The justification for requiring these tests was directly influenced by the growing Eugenics Movement. Literacy thus became intricately tied to an expanded conception of race and, consequently, the imagined worthiness of different ethnic and nationality groups. The 1917 Literacy Test Act, also referred to as the Immigration Act of 1917, limited migration to the United States and marked the IRL's eventual success. By that time, however, such tests had become seen as a proxy for presumably rigid, racialised, national characteristics, and the IRL pushed for even more restrictive measures. IRL members remained active beyond the First World War and contributed to the extension of immigration restriction policies in 1921 and 1924.