To develop and validate a scale, the Self-management of Dementia by Carers (SMDC). Mixed-methods were used. First, the domains of the SMDC Scale were identified through a systematic literature review and interviews with expert professionals and carers. Then the following psychometrics were performed: content and face validity, internal consistency, test-retest reliability, and construct validity. The final scale had 58-item grouped into 6 factors. The internal consistency and test-retest reliability coefficients were excellent. This scale can be used to determine carers’ ability to assist the person living with dementia to self-manage this condition in clinical practice and research.