Determination of skin sensitization potential is a critical toxicological endpoint in the safety assessment of new chemicals. Although the Guinea Pig Maximization Test (GPMT) and in vivo Local Lymph Node assay (LLNA) have traditionally been used to assess skin sensitization, recent activity has focused on the development of novel non-animal assays for this endpoint. As a culmination of these efforts, the Organization for Economic Cooperation and Development (OECD) has published test guidelines for non-animal skin sensitization testing to address several Key Events in the Adverse Outcome Pathway (indicated in the boxed area below):