Objective – The assessment of outcome for any purpose is not undertaken routinely in European mental health services. This paper discusses the merits of using outcome data to inform the planning of mental health care for individual patients, and provides practical advice to support the implementation of this new approach to working. Method – The use of outcomes in North America and Europe is briefly reviewed. A conceptual basis is proposed for routine outcome assessment – the ongoing measurement and use of outcome data to inform decisions about whether to continue, change or curtail treatment. A cognitive psychology model is developed which indicates that the routine use of outcomes will improve mental health care. Perceived problems with routine outcome assessment are discussed, and principles for implementation are identified. Results – Outcomes are used mainly for generating local-level (rather than patient-level) data in North America, and rarely used in Europe. The use of outcome data routinely may facilitate reflective clinical practice, a model of decision-making which leads to a higher quality of clinical care than automated problem-solving. One issue relates to the use of standardised assessments designed for research purposes in clinical settings, and this is being addressed through the development of a new generation of outcome measures which are explicitly designed for clinical use. However, most clinicians remain unconvinced of the benefits of routine outcome assessment, and relevant research is currently underway across Europe which will address this concern. Scientific principles to maximise quality and pragmatic principles to maximise the chances of successful implementation are identified. Conclusions – The routine use of outcomes will become increasingly prominent in European mental health services. This provides clinicians with an opportunity to improve the quality of clinical care offered to patients.