This study argues that a critical element in the success of an ecosystem service (ES) approach at any level is the higher qualitative valuation of local traditional ecological knowledge (TEK). As such, the objectives of this research were to illustrate the role of TEK in agroecological systems in Peru and to develop recommendations about this type of knowledge acquisition. The data were gathered using interviews and focus groups with subsistence farmers along with key informant interviews to elicit TEK at local and regional scales in five provinces in the Lake Titicaca region of Puno, Peru. Qualitative analysis revealed dominant themes of TEK provided by farmers and key informants, and how this knowledge can enhance the application of an ES approach for environmental management. Climate variability, predicting the timing of seasonal changes, water availability, and adapting the agricultural calendar and agricultural techniques were all central themes. This research concludes that environmental management decisions in the Puno region of Peru are being informed and improved through the use of TEK. Supporting previous research, we propose that agroecological systems, at their core, need to respect the integrity and sanctity of TEK and value it properly within any practical solution for environmental resource management.