Keeping a secret is often considered burdensome, with numerous consequences for well-being. However, there is no standardized measure of secrecy burden, and most studies focus on individual/cognitive burden without considering social/relational aspects. This research aimed to develop and validate a secrecy burden measure tapping both intrapersonal and interpersonal components. Study 1 used exploratory factor analysis to reveal a four-factor model of secrecy burden: Daily Personal Impact, Relationship Impact, Pull to Reveal, and Anticipated Consequences. Study 2 used confirmatory factor analysis to replicate this factor structure and found that each factor was uniquely associated with different emotional and well-being outcomes. Study 3 employed a longitudinal design and found that higher scores on each factor predicted lower authenticity and higher depression and anxiety 2 to 3 weeks later. Altogether, this research is the first step in standardizing a secrecy burden measure and applying it to real-world secrets and well-being outcomes.