The environmental knowledge of inhabitants residing in a highly biodiverse mountainous region of western Mexico with an important economic forestry sector was investigated. Indices of environmental knowledge, by average and through factor analysis, were developed and characterized using survey data collected in 2018 and 2021. These indices showed high levels of correlation and followed similar patterns of distributions. Ordinary least squares and quantile regressions were used to examine social, economic, demographic, and perceptions as determinant factors of the generated indices. Age and education were repeatedly found as important factors influencing environmental knowledge, while income and gender were consistently not significant factors. Furthermore, environmental knowledge was related to the quality of life. The index developed by factor analysis generated more significantly stable parameter results across percentiles of environmental knowledge. The indices were recommended for monitoring environmental knowledge in long-term studies.