Background: There is a gap in understanding the meaning and motives behind suicidal behaviour. Using the Ideal Type methodology, Jean Baechler systematically examined the internal logic of suicidal and self-harming behaviours. He developed a typology of eleven typical meanings/motives: Flight, Grief, Self-punishment, Vengeance, Crime, Blackmail, Appeal, Sacrifice, Transfiguration, Ordeal and Game. Aims: To develop and validate a standardized instrument to measure the motives/meanings of suicidal and self-harming behaviours, using Baechler's typology. Method: We developed a self-fill Likert questionnaire (Ideal Typical Meaning Questionnaire, ITMQ) covering ten of Baechler's eleven types. The questionnaire was completed by 147 patients within four weeks of attempting suicide or self-harm. The Death Attitude Profile-Revised (DAP-R) questionnaire was used to examine the concurrent validity of the Flight and the Transfiguration types and to explore the association between suicidal/self-harming motives and views about death. Results: The final 25-item ITMQ has an eight-factor structure (Appeal/Blackmail, Ordeal/Game, Vengeance, Self-punishment, Sacrifice, Flight, Grief and Transfiguration) supporting Baechler's theory. The types have adequate reliability. Correlations with the DAP-R gave some support for the concurrent validity of the Flight and Transfiguration types. Conclusions: The ITMQ is a measure of suicidal and self-harming motives/meanings based on a sound conceptual framework and could significantly contribute to the understanding of suicidal and self-harming behaviour in research and clinical settings.