The employment to population rate of high school-aged youth has fallen by about 20 percentage points since the late 1980s. One potential explanation is increased competition from substitutable labor, such as immigrants. I demonstrate that the increase in the population of less educated immigrants has had a considerably more negative effect on employment outcomes for native youth than for native adults. At least two factors are at work: there is greater overlap between the jobs that youth and less educated adult immigrants traditionally do, and youth labor supply appears more responsive to immigration-induced wage changes.