Abstract: Background matching, or crypsis, is a well-studied anti-predator defense used by organisms to prevent detection by visually hunting predators.  Some amphibians have the capacity to physiologically alter their coloration by mobilizing melanin under their skin, allowing them to better match their backgrounds. However, there are few studies which examine how well amphibians can detect differences in backgrounds and change accordingly. Changes in pigmentation are stimulated by a variety of physiological cues, but the role of chemical cues produced by predators is unknown.  In order to determine the resolution with which larval brook salamanders, Eurycea cirrigera, could detect background change, this study examined their response to a color gradient of backgrounds.  A second experiment quantified the effect of predator chemical cues on background matching ability.  Two populations of E cirrigera were used for the experiments, one sympatric with fish, the other allopatric to fish.  In the first experiment, images of larvae were collected after 90 minute periods spent on each of the five backgrounds ranging from black-brown to white-brown.  Average grey scale values of both background and larvae were obtained from these images.  Larvae significantly changed coloration according to the background on which they were placed.  In the second experiment, trials were conducted on the two extreme backgrounds using fish cued and non-fish cued water.  The results from this experiment revealed that the larvae were able to detect the presence of chemical cues and became significantly lighter in the presence of those cues.  There were no differences in the crypsis abilities of larvae from the two populations in either experiment.  Larvae can change to match a variety of backgrounds that they might encounter in the stream, which may afford them protection against visually hunting predators.  Predator cues influence larval background matching which can be maladaptive on certain backgrounds.  Larvae that are uanble to match their backgrounds may have decreased survivorship.