: To test the hypothesis of an inverse association between indicators of vascular disease and cognitive function in the general, stroke-free population. : A longitudinal, British civil service-based cohort study. Measures of vascular disease examined were prevalent at baseline or traced over a median of 11 years, between Phases 1 (1985-1988) and 5 (1997-1999) of data collection. Cognitive function was assessed at Phase 5 of data collection. : Twenty London-based Civil Service departments. : Four thousand one hundred forty-one men and 1,681 women, aged 46 to 68 when tested for cognitive function. : A battery of cognitive tests consisting of: memory test, Alice Heim 4, Mill-Hill, phonemic, and semantic fluency. : The occurrence of angina pectoris (P<.001), myocardial infarction (P=.02), all coronary heart disease (P<.001), and intermittent claudication (P=.004) was associated with poor cognitive function. These effects were independent of age and socioeconomic status. The association between indicators of vascular disease and cognitive function applied to the entire range of cognitive function measures examined in the study. : The findings support the view that vascular disease is predictive of poor cognitive function in the general population. The fact that presence of vascular disease was associated with diminished cognitive function even in a relatively young cohort has implications for the management of vascular disease.