We used a rational-empirical approach in the construction and validation of a cognitive activity scale for use with elderly populations. The scale development effort produced a 25-item scale with a reasonably high level of internal consistency in a sample of 200 elderly individuals. Scale scores were positively correlated with years of education and measures of various domains of cognitive ability. In a separate cross-validation sample, a similar pattern of reliability and validity coefficients was obtained. The full scale score was found to contribute significantly to the prediction of cognitive ability after controlling for the effects of age, education, and gender. Two subscales (Higher Cognitive Abilities and Frequent Cognitive Abilities) and a measure of self-reported maintenance of cognitive activity were also developed. In a separate study, the maintenance score was found to differ significantly between the validation sample and a sample of individuals with a history of neurological disorder, with a moderate effect size (d approximately = .7). Further cross-validation studies in minority groups and groups of varying socioeconomic status will be critical in establishing the research and clinical value of the scale and subscales.