Worldwide, influenza virus causes substantial illness and death and considerable public health costs. Like other countries, Peru experiences a significant number of influenza cases. The epidemiology of influenza virus in tropical and low- to middle-income countries and the role they play in global influenza ecology remains unclear. One outstanding question is whether a global source–sink dynamic exists.   In recent years, prospective community-based influenza-like illness (ILI) surveillance cohorts were established in multiple regions of Peru, providing a unique opportunity to examine the epidemiology of human influenza virus.  In 2009, the United States Navy Medical Research Unit No. 6 (NAMRU-6), the Centers for Disease Control and Prevention (CDC), and the Peruvian Ministry of Health established a community-based prospective ILI cohort (Proyecto Influenza) in 4 ecologically distinct regions of Peru. This study leverages this cohort to examine Influenza seasonality across diverse ecosystems in Peru.