The study presented here uses data from the NORC General Social Surveys to explore the effects of measurable school characteristics on student achievement. What separates this study from many others is the use of aggregate data on older cohorts, usually associated with research on the influence of school inputs on earnings. We fmd substantively large effects, similar in size to those found in many earnings-focused studies. Our results point to the impor- tance of aggregation in modeling the relationship between school inputs and student outcomes, bringing into question causal interpretations of the results of studies using aggregate data to assess school input effects. S CHOOLS differ markedly in quality and their ability to promote student achievement. Yet, simple measures of school inputs, such as student-teacher ratios, generally have not been found to capture school quality differences that influence student outcomes. The 1966 Coleman Report, the result of an extensive nationally representative study of schools, showed little school quality effect on student test scores once family background characteristics were ac- counted for. These results were bolstered by Hanushek's (1986) summary of research on the impact of school charac- teristics on achievement in which he found no measurable characteristic of schools that consistently contributed to stu- dent achievement. A recent meta-analysis of the same stud- ies that Hanushek used indicated positive relationships be- tween some school inputs and student outputs, undetected with Hanushek's simpler summary methods (Hedges, Laine, and Greenwald (1994)). Yet, even meta-analyses and studies at the level of micro data in general that have found signifi- cant effects of school inputs on achievement have tended not to find substantively large and consistent effects (Childs and Shakeshaft (1986), Glass and Smith (1979)). In light of this history, the corresponding literature on the impact of school characteristics on later earnings seems surprising. A series of studies using aggregate school input data at the state or district level have concluded that school inputs can substantially increase returns to education, as well as educa- tional attainment (e.g., Akin and Garfinkel (1977), Card and Krueger (1992), Johnson and Stafford (1973), Link and Ratledge (1975), and Rizzuto and Watchel (1980). Card and Krueger (forthcoming) provide a review.) What accounts for the discrepancies between these two literatures? A number of alternatives have been suggested (Betts (1996), Burtless (1996)). First, the two literatures ex- amine different outcomes. Measured school quality may in- crease the impact of schools on earnings, even if it does not increase their impact on academic achievement (Card and Krueger (1992)).' Second, studies that use earnings as the dependent variable and find positive effects may have insuf- ficient controls for family background. This potential prob- lem is particularly relevant in light of findings that there is generally a positive raw correlation between spending and academic achievement but that this relationship usually dis- appears after family background characteristics are taken into consideration (Hanushek (1986)). Third, studies that focus on earnings have either ignored the potential effects of local labor markets (Johnson and Stafford (1973)) or, as in the case of the work by Card and Krueger (1992), have identified effects by comparing the earnings of individuals who grew up in different locations, but currently work in the same area. The first of these procedures is potentially problematic since the returns to skills learned in school may vary by location. The latter circumvents this problem, but may be biased since migrants are self-selected (Heckman, Layne-Farrar and Todd (1995)). Alternatively, the conflict between the findings of positive school quality effects on earnings but not on academic achievement may be due to differences in the nature of the data used. The data in the two literatures have consistently differed in two ways. First, income analyses have tended to use historical information on school characteristics, while achievement analyses have tended to use contemporaneous data. This difference arises because more reliable data on achievement is available for recent cohorts, while income information is mote stable for older cohorts. Second, earn- ings focused research almost exclusively has used aggregate measures of school inputs, matching workers with the aver- age inputs in the school district or state in which they grew up.2 Studies using achievement as the outcome measure, on the other hand, have tended to use micro level data, matching students to the precise school or classroom they attended. In the study presented here, we use aggregate historical data on school inputs to predict the scholastic achievement of people in the same three cohorts used by Card and Krueger (1992) in their assessment of the effects of school quality on income returns to education-those born in the 1920s, the 1930s and the 1940s. By doing this we will be better able to distinguish among some of the possible causes of