We hypothesized that neighborhood socioeconomic context would be most strongly associated with risk of myocardial infarction (MI) for smaller "neighborhood" definitions. We used data on 487 non-fatal, incident MI cases and 1873 controls from a case-control study in Washington State. Census data on income, home ownership, and education were used to estimate socioeconomic context across four neighborhood definitions: 1 km buffer, block group, census tract, and ZIP code. No neighborhood definition led to consistently stronger associations with MI. Although we confirmed the association between neighborhood socioeconomic measures and risk of MI, we did not find these associations sensitive to neighborhood definition.