Complexity and uncertainty are long-standing challenges for global development projects. Coping with both requires flexibility and adaptation, the ability to identify unexpected circumstances, seize opportunities, and respond to threats. Vigilance is critical; it resides within the domains of monitoring, evaluation, and learning. In practice, maintaining vigilance is difficult, partly because effective vigilance has a dual nature. Normal, Type 1 vigilance, is anchored in knowing what to look for. It demands focus and attention to designated indicators. Type 2 vigilance looks for what project preparations failed to anticipate. It demands defocusing and openness; it sits outside contemporary design of monitoring and evaluation as it must question the assumptions in project design and implementation. We consider the role of both types of vigilance in global development and difficulties in maintaining both simultaneously. We identify pathways for improving the practice of vigilance and suggest practical steps in a template for pilot efforts.