While there is a large body of research demonstrating that having an abortion is not associated with adverse mental health outcomes, less research has examined which factors may contribute to elevated levels of mental health symptoms at the time of abortion seeking. This study aims to develop and validate a new tool to measure dimensions of psychosocial burden experienced by people seeking abortion in the United States. To develop scale items, we reviewed the literature including existing measures of stress and anxiety and conducted interviews with experts in abortion care and with patients seeking abortion. Thirty-five items were administered to 784 people seeking abortion at four facilities located in three U.S. states. We used exploratory factor analysis (EFA) to reduce items and identify key domains of psychosocial burden. We assessed the predictive validity of the overall scale and each sub-scale, by assessing their associations with validated measures of perceived stress, anxiety, and depression using multivariable linear regression models. Factor analyses revealed a 12-item factor solution measuring psychosocial burden seeking abortion, with four subdomains: structural challenges, pregnancy decision-making, lack of autonomy, and others' reactions to the pregnancy. The alpha reliability coefficients were acceptable for the overall scale (α = 0.83) and each subscale (ranging from α = 0.82-0.85). In adjusted analyses, the overall scale was significantly associated with stress, anxiety and depression; each subscale was also significantly associated with each mental health outcome. This new scale offers a practical tool for providers and researchers to empirically document the factors associated with people's psychological well-being at the time of seeking an abortion. Findings suggest that the same restrictions that claim to protect people from mental health harm may be increasing people's psychosocial burden and contributing to adverse psychological outcomes at the time of seeking abortion.