In response to an amended consent decree entered to conclude litigation between EPA and the Natural Resources Defense Council (NRDC), the Agency released on, January 31, 2003, an atrazine Interim Reregistration Eligibility Decision (IRED) that was based, in part, on an assessment of the pesticide's ecological risk. However, several studies concerning the potential effects of atrazine on amphibian development were published in a time frame that prevented the Agency from completing a rigorous evaluation of these data for inclusion in the January 31, 2003 IRED. In accordance with the consent decree, EPA has developed this white paper as the basis for an SAP meeting to be held on June 17 - 20, 2003. The white paper provides an overview of relevant studies published in the scientific literature and studies submitted by the registrant through February 28, 2003. This white paper assesses: o the strengths and limitations of the available studies to evaluate the extent to which atrazine may elicit developmental effects in amphibians; o the extent of concordance for the entire body of information derived from these laboratory and field studies to assess the plausibility that atrazine can cause developmental effects; and if so, o the nature and strength of associated dose-response relationships.