Abstract: Variation in toxicity among formulations and species makes it difficult to extrapolate results to all species and all formulations of herbicides. We exposed larval wood frogs (Lithobates sylvaticus) from four populations to two glyphosate-based herbicides, Roundup Weed and Grass Control™ and Roundup WeatherMax™. 96 hour LC50 values for both formulations varied among the populations (RWGC: 0.14 to 1.10 mg acid equivalents (a.e.)/L; RWM: 4.94 to 8.26 mg a.e./L), demonstrating that toxicity varies among the formulations and that susceptibility may differ among populations. [Christopher Edge, Meghan Gahl, Dean Thompson, Chunyan Hao & Jeff Houlaha (2014). Variation in amphibian response to two formulations of glyphosate-based herbicides. Environmental Toxicology and Chemistry, online Aug 16] ${imageDescription} Comment