Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous contaminants emanating from multiple sources in the environment. When conducting environmental monitoring of PAHs, it is imperative to examine sources of PAHs to know if they are coming from the source or sources you are investigating. This presentation will cover the fundamentals of what chemical fingerprinting of PAHs works, the basis of diagnostic ratios and a walk through of an online data portal that allows everyone to chemically fingerprint and determine sources of the PAHs in their environmental data.