Introduction and Aim: Suboptimal health-related quality of life and lowered employment rates found in a previous study in young adults (YA) with congenital coagulation disorders (CCD) in the Netherlands underline the need for more insight into professional functioning of YA with CCD and into determinants of professional functioning. Methods: Young adults (18-30 years) with CCD participated in a cross-sectional study. Professional functioning was assessed with the Work Productivity and Activity Impairment questionnaire (WPAI). Potential determinants were assessed with the Course of Life Questionnaire (CoLQ), Pediatric Quality of Life Inventory Young Adult version (PedsQL_YA), Illness Cognition Questionnaire (ICQ) and Haemophilia Activities List (HAL). Logistic regression analyses were performed in the complete sample of YA with CCD, and in YA men with haemophilia separately, to examine determinants of WPAI outcomes. Results: Ninety-four YA (77 men; mean age 24.1 years, SD 3.5 and 17 women; mean age 24.5 years, SD 3.8) with CCD (74% haemophilia A/B) participated. 74.5% of YA were