Mental health and social care services networks aim to provide patients with continuity of care and support their recovery. There is, however, no conclusive evidence of their effectiveness. Since 2011, Belgium has been implementing a nation-wide reform of mental health care by commissioning service networks. Using a case–control design, we assessed the reform’s effectiveness for continuity of care, social integration, quality of life, and re-hospitalization for 1407 patients from 23 networks. Greater reform exposure was associated with a slight improvement in continuity of care, but not with other outcomes. We concluded that service networks alone do not affect patient-level outcomes.