Using the right amount of pesticide at the right time can improve farm profits. However, uninformed users may apply more than is needed, resulting in lower profits and an increased threat to surface and groundwater resources. In some areas, site conditions, pesticide properties, and/ or applicator practices increase the risk of groundwater contamination even when pesticides are used according to label directions. In most rural areas, pesticides can be used according to label directions without causing groundwater contamination. This guide focuses on the movement of agricultural pesticides to groundwater. It is intended to raise awareness of the site factors, pesticide properties, and applicator practices that increase the risk of groundwater contamination. The last section of the guide discusses the Environmental Protection Agency's (EPA) drinking water standards and the potential health effects of consuming water contaminated with pesticides. The guide is written for pesticide users and rural residents concerned about the quality of ground water resources.