Environmental forensics is the application of defensible scientific methods to address questions related to release histories and sources of contamination in the environment. Environmental forensics generally involves the reconstruction of past environmental events, such as the timing, types and amounts, and sources of chemical releases to the environment. Exponent scientists have been leaders in the many aspects of the field since its inception 30+ years ago and have been at the forefront of developing and applying and publishing on new techniques. Questions requiring environmental forensic applications usually relate to understanding the extent, duration, and responsibility for environmental contamination sites in a regulatory and/or legal context. These approaches are also integral to environmental due diligence for mergers and acquisitions and remediation cost recovery. Techniques such as chemical fingerprinting, chemical fate and transport modeling, hydrogeological investigation, and reconstructing operational histories, among others are at the heart of many investigations. These and newer techniques, such as multivariate receptor statistical modeling, continue to evolve and have become more sophisticated over time, as have the types of problems to which they are applied. Scenarios in which environmental forensics have been applied have ranged from remote Arctic environments to urban sediments. In both extremes, the chemical condition of the environment – i.e., the background or baseline – is a central part of any investigation. It is upon this background that additional contamination from one or several responsible parties is overlain.