||Beginning in 1892, immigrants to the United States were subject to a medical inspection, created to restrict the entry of persons with a eloathsome or dangerous contagiousn disease or mental deficiency. Ellis Island, which received over 10 million newcomers between 1900 and 1914, served as the largest ever medical screening facility. Far from reflecting a unified policy, the medical inspection offered a complicated compromise amidst a swirl of competing interests. Many industrialists blamed the waves of Southern and Eastern European immigrants for urban joblessness, filth, unrest, overcrowding, and disease. In an era of depression, labor groups opposed immigrant competitors for scarce jobs. Nativists believed immigrants could not overcome their defects because these were genetically transmitted. Germ theory proponents recognized communication of microorganisms as the problem, with controlling the spread of infections as the solution. Many Progressive reformers held that the scientific screening of immigrants offered a systematic solution for the disorder. Dozens of immigrant aid societies struggled to attenuate the effects of the inspection, and as depression subsided after 1900, employers, too, favored the influx of immigrants. This paper examines the social and political basis for the inspection, its realization at Ellis Island, and the reasons for its inability to debar large numbers of immigrants.