Background: The integration of psycho-oncology into the medical care of cancer patients requires a transparent, reliable, and valid assessment of psychosocial stress. The Basic Documentation for Psycho-Oncology (PO-Bado), including a short version and a breast cancerspecific version, is such an instrument. The purpose of this article is to present the current stage of development of the 3 versions. Patients and Methods: All versions of the PO-Bado were developed and psychometrically evaluated based on the empirical analysis of multiple oncological samples. External criteria for the validation and determination of cut-off scores were the Hospital Anxiety and Depression Scale, the Questionnaire on Stress in Cancer Patients, and the EORTC Quality of Life Questionnaire. Inter-rater reliability was examined by different psycho-oncologists who independently rated PO-Bado interviews. Results: Three versions of the PO-Bado are presented: the standard version (PO-Bado, 17 items), the short form (PO-Bado SF, 7 items), and the breast cancerspecific version (PO-Bado BC, 21 items). A manual and interview guideline are provided for all versions. By now, the standard version has been implemented throughout Germany and includes data of 6,365 patients. Conclusion: A consistent nationwide implementation of the PO-Bado for the assessment of psychosocial stress in cancer patients would contribute to the improvement of medical care.