The purpose of this study was to define the risk for adults with congenital heart disease who underwent cardiac catheterization and to propose a precatheterization risk scoring system. Data were prospectively collected using a multicenter registry of the Congenital Cardiovascular Interventional Study Consortium. The occurrence of serious adverse events (SAE) was correlated with 12 predefined variables. Catheterization RISk in Adult patients (CRISA) score was derived using multivariate logistic regression with backward elimination model selection method. The CRISA score was compared with the American Society of Anesthesiology score and a consensus-derived, 20-point risk score based on their ability to predict SAE. From June 2008 to September 2017, 300 adjudicated SAE's occurred in 7317 catheterization procedures (overall SAE rate 4.1%) performed in adults over 18 years of age at 27 contributing centers. Nine of the 12 tested variables were ultimately included in the CRISA score. CRISA score positively correlated with risk of SAE, and was superior to American Society of Anesthesiology and the 20-point risk score in predicting SAE. Minimal (CRISA score 0 to 2), low (3 to 7), moderate (8 to 10) and high (≥11) risk categories were identified, corresponding to 0.5%, 3.2%, 7.9%, and 16.7% risk of SAE, respectfully. In conclusion, the CRISA score reliably predicts risk of SAE in adults with congenital heart disease who underwent cardiac catheterization and may be useful for preprocedural risk assessment.