tGlyphosate-based herbicides are currently the most commonly used herbicides in the world. They havebeen shown to affect survival, growth, development and sexual differentiation of tadpoles under chroniclaboratory exposures but this has not been investigated under more environmentally realistic condi-tions. The purpose of this study is (1) to determine if an agriculturally relevant exposure to RoundupWeatherMax®, a relatively new and understudied formulation, influences the development of wood frogtadpoles (Lithobates sylvaticus) through effects on the mRNA levels of genes involved in the control ofmetamorphosis; (2) to compare results to the well-studied Vision® formulation (containing the isopropy-lamine salt of glyphosate [IPA] and polyethoxylated tallowamine [POEA] surfactant) and to determinewhich ingredient(s) in the formulations are responsible for potential effects on development; and (3) tocompare results to recent field studies that used a similar experimental design. In the present labora-tory study, wood frog tadpoles were exposed to an agriculturally relevant application (i.e., two pulses)of Roundup WeatherMax® and Vision® herbicides as well as the active ingredient (IPA) and the POEAsurfactant of Vision®. Survival, development, growth, sex ratios and mRNA levels of genes involved intadpole metamorphosis were measured. Results show that Roundup WeatherMax® (2.89 mg acid equiv-alent (a.e.)/L) caused 100% mortality after the first pulse. Tadpoles treated with a lower concentration ofRoundup WeatherMax® (0.21 mg a.e./L) as well as Vision® (2.89 mg a.e./L), IPA and POEA had an increasedcondition factor (based on length and weight measures in the tadpoles) relative to controls at Gosnerstage (Gs) 36/38. At Gs42, tadpoles treated with IPA and POEA had a decreased condition factor. Alsoat Gs42, the effect on condition factor was dependent on the sex of tadpoles and significant treatmenteffects were only detected in males. In most cases, treatment reduced the normal mRNA increase of keygenes controlling development in tadpoles between Gs37 and Gs42, such as genes encoding thyroid hor-mone receptor beta in brain, glucocorticoid receptor in tail and deiodinase enzyme in brain and tail. Weconclude that glyphosate-based herbicides have the potential to alter mRNA profiles during metamor-phosis. However, studies in natural systems have yet to replicate these negative effects, which highlightthe need for more ecologically relevant studies for risk assessment.