Of 54 federal immunization project areas in the United States, 13 areas with low measles incidence rates in 1977 and 1978 and 10 with high measles incidence rates were compared for differences in surveillance systems, demography, vaccine utilization, school immunization laws, and immunity levels. There was no significant difference between the low incidence and high incidence group for any examined parameter of demographic characteristics, vaccine utilization, or surveillance systems. However, in the low incidence group, school immunization laws were found to be more comprehensive and more strictly enforced with a statewide policy of exclusion from school of noncompliant students. Furthermore, immunization levels were similar for two-year-olds in both groups but were significantly higher for school entrants in the low incidence group. In all public health efforts to control or eliminate measles, priority should be given to establishing and strictly enforcing comprehensive school immunization laws.