Statebuilding has been informed and captured by reductionist, linear change models. Defined by technocratic approaches to public sector (re)building and reform-it has been monitored, measured and evaluated by New Public Management artefacts such as log-frames and Results-Based Management. Through a case study on the capacity development of the Royal Solomon Islands Police Force, I explore the possibilities for using complexity theory to better understand, manage, and monitor capacity development interventions. The analysis of interview data with police practitioners from both sides of the intervention-advisors and local counterparts-reveals the explanatory power of complexity concepts (such as interconnectedness, emergence, initial conditions, and non-linear change) in ways that could inform a rethink of how we frame public sector capacity building interventions.