No validated measures are currently available to assess women's ability to achieve their reproductive intentions, also referred to as “reproductive autonomy.” We developed and validated a multidimensional instrument that can measure reproductive autonomy. We generated a pool of 26 items and included them in a survey that was conducted among 1,892 women at 13 family planning and 6 abortion facilities in the United States. Fourteen items were selected through factor analysis and grouped into 3 subscales to form a Reproductive Autonomy Scale: freedom from coercion; communication; and decision‐making. Construct validity was demonstrated by a mixed‐effects model in which the freedom from coercion subscale and the communication subscale were inversely associated with unprotected sex in the past three months. This new Reproductive Autonomy Scale offers researchers a reliable instrument with which to assess a woman's power to control matters regarding contraceptive use, pregnancy, and childbearing, and to evaluate interventions to increase women's autonomy domestically and globally.