This study was conducted to investigate the effects of eco-schools on elementary school students' environmental literacy levels. Data of the study were gathered from 316 students enrolled to two elementary schools. One of the schools was determined as experimental group (n = 156) and students attending this school received eco-school application. The other school was set as control group (n = 160) and students enrolled to this school received traditional school application. Environmental Literacy Questionnaire with four subscales; environmental knowledge, attitudes, uses and concerns, was used to determine students' environmental literacy levels. Results revealed that there were significant differences between control and experimental groups of different grade levels in terms of the all subscales of Environmental Literacy Questionnaire in favor of experimental group. (Contains 7 tables, 1 figure and 1 footnote.)