Background. The reform of mental health services needs to be guided by an overall conceptual framework. Such a framework is important to avoid many risks, including extrapolating from a specific service site to other services, without taking into account local and regional variables.

Methods. A conceptual framework, the ‘matrix model’, is proposed. This model has been developed using the most relevant information that is necessary for describing and interpreting mental health services data as well as patient-based information.

Results. The ‘matrix model’ has two dimensions: the geographical, which refers to three levels (country, local and patient) and the temporal, which refers to three phases (inputs, processes and outcomes). Using these two dimensions a nine-cell matrix is constructed to bring into focus critical issues for mental health services. The relevance of each level and each phase is briefly presented.

Conclusions. The matrix is intended to assist clinicians, planners and researchers to deal with clinical phenomena, organizational issues, and research questions that share a degree of complexity that render inadequate analyses and the interventions made only at one level. The matrix model applies particularly to mental health systems of care that are provided with a public health framework, and is less useful for contexts that consist of clinicians offering only one-to-one treatments, within fragmented programmes of care.