This study presents the development of the 5C scale, a validated measure assessing the psychological antecedents of vaccination: confidence, complacency, constraints, calculation, and collective responsibility. The 5C scale was developed through three cross-sectional studies involving nearly 2,800 participants. Study 1 used factor analysis to develop an initial scale and assess the convergent, discriminant, and concurrent validity of the sub-scales. Study 2 tested the scale's performance with a sample representative of the German population and assessed the potential need for vaccine-specific wording. Study 3 compared the novel scale with six existing measures of vaccine hesitancy. The 5C scale was found to be reliable and valid, with a long (15-item) and short (5-item) version. The 5C sub-scales correlated with relevant psychological concepts, such as attitude (confidence), perceived personal health status and invulnerability (complacency), self-control (constraints), preference for deliberation (calculation), and communal orientation (collective responsibility). The new scale provided similar results when formulated in a general vs. vaccine-specific way. In a comparison of seven measures, the 5C scale was consistently among the scales that explained the highest amounts of variance in analyses predicting single vaccinations (between 20% and 40%). The 5C scale provides a novel tool to monitor psychological antecedents of vaccination and facilitates diagnosis, intervention design, and evaluation. Its short version is suitable for field settings and regular global monitoring of relevant antecedents of vaccination. The 5C scale assesses the psychological antecedents of vaccination, including confidence, complacency, constraints, calculation, and collective responsibility. The scale was developed based on established theoretical models of vaccine hesitancy and acceptance and relates these to psychological models to explain health behavior. The 5C scale was validated through three studies, resulting in a reliable and valid long (15-item) and short (5-item) version of the scale. The 5C scale provides a comprehensive assessment of the psychological antecedents of vaccination and is suitable for use in research and practice.This study presents the development of the 5C scale, a validated measure assessing the psychological antecedents of vaccination: confidence, complacency, constraints, calculation, and collective responsibility. The 5C scale was developed through three cross-sectional studies involving nearly 2,800 participants. Study 1 used factor analysis to develop an initial scale and assess the convergent, discriminant, and concurrent validity of the sub-scales. Study 2 tested the scale's performance with a sample representative of the German population and assessed the potential need for vaccine-specific wording. Study 3 compared the novel scale with six existing measures of vaccine hesitancy. The 5C scale was found to be reliable and valid, with a long (15-item) and short (5-item) version. The 5C sub-scales correlated with relevant psychological concepts, such as attitude (confidence), perceived personal health status and invulnerability (complacency), self-control (constraints), preference for deliberation (calculation), and communal orientation (collective responsibility). The new scale provided similar results when formulated in a general vs. vaccine-specific way. In a comparison of seven measures, the 5C scale was consistently among the scales that explained the highest amounts of variance in analyses predicting single vaccinations (between 20% and 40%). The 5C scale provides a novel tool to monitor psychological antecedents of vaccination and facilitates diagnosis, intervention design, and evaluation. Its short version is suitable for field settings and regular global monitoring of relevant antecedents of vaccination. The 5C scale assesses the psychological antecedents of vaccination, including confidence, complacency, constraints, calculation, and collective responsibility. The scale was developed based on established theoretical models of vaccine hesitancy and acceptance and relates these to psychological models to explain health behavior. The 5C scale was validated through three studies, resulting in a reliable and valid long (15-item) and short (5-item) version of the scale. The 5C scale provides a comprehensive assessment of the psychological antecedents of vaccination and is suitable for use in research and practice.