Background Community level interventions to improve maternal and child health have been supported and well evaluated in resource poor settings, but less so in developed countries. PRISM - Program of Resources, Information and Support for Mothers - was a primary care and community-based cluster-randomised trial in sixteen municipalities in Victoria, Australia, which aimed to reduce depression in mothers and improve their physical health. The aim of this paper is to report the longer term outcomes of PRISM and to reflect on lessons learned from this universal community intervention to improve maternal health. Methods Maternal health outcome data in PRISM were collected by postal questionnaire at six months and two years. At two years, the main outcome measures included the Edinburgh Postnatal Depression Scale (EPDS) and the SF-36. Secondary outcome measures included the Experience of Motherhood Scale (EOM) and the Parenting Stress Index (PSI). A primary intention to treat analysis was conducted, adjusting for the randomisation by cluster. Results 7,169/18,424 (39%) women responded to the postal questionnaire at two years -3,894 (40%) in the intervention arm and 3,275 (38%) in the comparison arm. Respondents were mostly representative on available population data comparisons. There were no differences in depression prevalence (EPDS=13) between the intervention and comparison arms (13.4% vs 13.1%; ORadj = 1.06, 95%CI 0.91-1.24). Nor did women's mental health (MCS: 48.6 vs 49.1) or physical health scores (PCS: 49.1 vs 49.0) on the SF-36 differ between the trial arms. Conclusion Improvement in maternal mental and physical health outcomes at the population level in the early years after childbirth remains a largely unmet challenge. Despite the lack of effectiveness of PRISM intervention strategies, important lessons about systems change, sustained investment and contextual understanding of the workability of intervention strategies can be drawn from the experience of PRISM.