This study relates various types of educational spending to mean mathematics achievement and its social distribution among students. A nationally representative database of 7,217 twelfth graders was developed by linking the 1992 National Assessment of Educational Progress in mathematics to the U.S. Common Core of Data and the School District Data Book. Through applying Hierarchical Linear Modeling to the database, the study found that spending on instruction and capital expenditures, while not related to mean achievement levels, were related to differences in achievement between SES groups; lower spending levels are associated with greater achievement gaps within schools.