Background: Recently, the Nijmegen Continuity Questionnaire (NCQ) was developed. It aims to measure continuity of care from the patient perspective across primary and secondary care settings. Initial pilot testing proved promising. Aim: To further examine the validity, discriminative ability, and reliability of the NCQ. Design: A prospective psychometric instrument validation study in primary and secondary care in the Netherlands. Method: The NCQ was administered to patients with a chronic disease recruited from general practice (n = 145) and hospital outpatient departments (n = 123) (response rate 76%). A principal component analysis was performed to confirm three subscales that had been found previously. Construct validity was tested by correlating the NCQ score to scores of other scales measuring quality of care, continuity, trust, and satisfaction. Discriminative ability was tested by investigating differences in continuity subscores of different subgroups. Test-retest reliability was analysed in 172 patients. Results: Principal factor analysis confirmed the previously found three continuity subscales-personal continuity, care provider knows me; personal continuity, care provider shows commitment; and team/cross-boundary continuity. Construct validity was demonstrated through expected correlations with other variables and discriminative ability through expected differences in continuity subscores of different subgroups. Test-retest reliability was high (the intraclass correlation coefficient varied between 0.71 and 0.82). Conclusion: This study provides evidence for the validity, discriminative ability, and reliability of the NCQ. The NCQ can be of value to identify problems in continuity of care.