In recent years the evidence base for psychological interventions in low- and -middle-income countries (LMIC) has rapidly accrued, demonstrating that task-shifting models result in desired outcomes. Next, it is important to look at how this evidence translates into practice. In doing so, this paper argues that the field of global mental health might benefit from applying a system theory or system science perspective. Systems thinking aims to understand how different components are connected and interdependent within a larger emergent entity. At present much of the research efforts into psychological interventions in LMIC are focusing on single interventions, with little focus on how these interventions sit in, or influence, a larger system. Adopting systems theory and system dynamics tools can help in; (i) better analyzing and understanding the key drivers of mental health problems and services, (ii) optimizing mental health services; and (iii) understanding the organization of people, institutions and resources required for rolling out and scaling-up mental health services. This paper reflects on some of these merits of a systems perspective, as well as provides some examples.