Background To understand how blood pressure (BP) from midlife and beyond is related to cognition in older age, a lifespan approach is needed. We assessed the associations of BP levels and variability from midlife on with subsequent cognitive change. Methods and Results The ARIC (Atherosclerosis Risk in Communities) Study participants underwent 4 clinic BP measurements (visit 1, 2, 3, and 4 BPs) between 1987 and 1998, and their mean levels and average real variability (ARV) were assessed as exposures. A global cognitive z score, estimated from the Delayed Word Recall Test, Digit Symbol Substitution Test, and Word Fluency Test scores, was calculated at 1996 to 1998 (visit 4) and 2011 to 2013 (visit 5). Among 11 408 participants (mean age, 54 years; 56% women; 21% black race), mean systolic BP (SBP)/diastolic BP (DBP) level was 123/72 mm Hg, and ARVSBP/ARVDBP was 11/7 mm Hg. With linear mixed models, 1‐SD increases of ARVSBP (standardized regression coefficient [95% confidence interval], −0.03 [−0.04 to −0.01] points) and ARVDBP (standardized regression coefficient [95% confidence interval], −0.02 [−0.03 to −0.002] points; both P