This paper presents evidence that recent aptitude test score decline is signaling a significant deterioration in the quality of entering cohorts of workers. The impact of general intellectual achievement (GIA) on productivity; trends in the GIA of the adult populations, students, and working adults; accounting for the labor quality growth when credentials signal GIA; and the productivity consequences of test score decline are discussed. The test score decline, which began around 1967, was roughly equal to the learning that takes place in 1.25 years of high school. The resulting wage rate decline was determined to be 7.1%. New estimates of the quality of the work force are developed that take into account improvements in the quality and quantity of education. Although substantial evidence links the decline in productivity with test score decline, the timing may seem inappropriate in linking the two factors causally. Teenagers play only a minor role in the economy; thus, a decline in their test scores cannot account for a simultaneous drop in productivity growth. Nevertheless, declines in test scores for teenagers since the late 1960s may be responsible for the non-appearance of the anticipated rebound in productivity growth forecast for the 1980s. Eight figures, eight data tables, and 81 references are provided. (TJH)