The occurrence of motor vehicle accidents (MVAs) was studied prospectively in a sample of 500 drivers aged 19-88. Over a 4-year interval from 1991 to 1995, 36% of these drivers had a minor accident and 9% had a serious (injury-producing) accident. Data collected in 1991 demonstrated that crashes could be predicted from a combination of pre-existing characterological, situational, and behavioral risk factors, and that these risk factors largely explained sex and age differences in accident rates. The best predictors of future MVAs were younger age, high hostility in combination with poor self-esteem, residence in a larger city, recent relocation, high job stress, prior MVAs, and self-reported tendencies to speed and disregard traffic rules. Failure to wear seat belts did not predict accidents but did significantly influence the severity of accidents that did occur; that is, those who had earlier reported using seat belts 'always' were less likely than others to be injured when accidents did occur. Financial stress increased the likelihood of involvement in more serious accidents.