Background The extent to which change in cardiovascular health (CVH) in midlife reduces risk of subsequent cardiovascular disease and mortality is unclear. Methods and Results CVH was computed at 2 ARIC (Atherosclerosis Risk in Communities) study visits in 1987 to 1989 and 1993 to 1995, using 7 metrics (smoking, body mass index, total cholesterol, blood glucose, blood pressure, physical activity, and diet), each classified as poor, intermediate, and ideal. Overall CVH was classified as poor, intermediate, and ideal to correspond to 0 to 2, 3 to 4, and 5 to 7 metrics at ideal levels. There 10 038 participants, aged 44 to 66 years that were eligible. From the first to the second study visit, there was an improvement in overall CVH for 17% of participants and a decrease in CVH for 21% of participants. At both study visits, 28%, 27%, and 6% had poor, intermediate, and ideal overall CVH, respectively. Compared with those with poor CVH at both visits, the risk of cardiovascular disease (hazard ratio [HR], 0.26; 95% CI, 0.20–0.34) and mortality (HR, 0.35; 95% CI, 0.29–0.44) was lowest in those with ideal CVH at both measures. Improvement from poor to intermediate/ideal CVH was also associated with a lower risk of cardiovascular disease (HR, 0.67; 95% CI, 0.59–0.75) and mortality (HR, 0.80; 95% CI, 0.72–0.89). Conclusions Improvement in CVH or stable ideal CVH, compared with those with poor CVH over time, is associated with a lower risk of incident cardiovascular disease and all‐cause mortality. The change in smoking status and cholesterol may have accounted for a large part of the observed association.