Project GREEN (Garden Resources for Environmental Education Now) is a garden program designed to help teachers integrate environmental education into their classroom using a hands-on tool, the garden. The objectives of this research project were to 1) develop an interdisciplinary garden activity guide to help teachers integrate environmental education into their curricula and 2) evaluate whether children developed positive environmental attitudes by participating in the activities. Students participating in the Project GREEN garden program had more positive environmental attitude scores than those students who did not participate. Second-grade students in the experimental and control groups had more positive environmental attitudes than fourth-grade students. In addition, this research found a significant correlation between the number of outdoor related activities students had experienced and their environmental attitudes.