Although the proportion of teenagers in the labor force generally increases during economic expansions, the labor force participation rate for 16- to 19-year-olds changed very little during the exceptional labor market conditions of the mid-1990s. In July 2000, the labor force participation rate for teens was at its lowest level since 1965. Between 1994 and 2000, the July labor force participation rate for teens declined from 65.4% to 62.3%. This decline occurred even as the unemployment rate for teens was falling to its lowest level in more than 3 decades. Data from the Current Population Survey indicate that an increasing rate of school enrollment in the summer was a factor behind the decline in teen summer labor force participation. Between 1994 and 2000, the percentage of teens enrolled in school in July increased from 19.5% to 27.0%. Decreases in the labor force participation rates for both students and nonstudents also contributed to the overall decline in teen labor force participation. Data for October of each year indicate that labor force participation among high school students also dropped during the school year (from 42.1% in 1994 to 37.8% in 2000). However, the October labor force participation rate of nonstudents increased from 70.8% in 1994 to 75.9% in 2000. (MN)