Ephemeral, fishless wetlands with open canopies are known to be quality breeding habitats for pond-breeding amphibians. Yet many wetlands including these are commonly invaded by exotic plants, resulting in vegetation shifts from diverse native vegetation to monotypic stands of novel material. I tested the hypothesis that an invasive grass, reed canary grass (Phalaris arundinacea), would reduce survival, growth, and development rates of four tadpole species relative to a mixture of native grasses. I manipulated grass type and amount in fully replicated mesocosm experiments that contained American Toads (Anaxyrus americanus), Cope's Gray Treefrogs (Hyla chrysoscelis), Pickerel Frogs (Lithobates palustris), or Wood Frogs (Lithobates sylvatica). Counter to expectations, I found little evidence that diverse vegetation enhanced wetland quality for amphibians, because the quantity of decomposing plant matter influenced tadpole performance more than type of plant matter. Growth and development of tadpoles was generally not affected by RCG, indicating that this invasive grass produced minimal direct (e.g., toxic alkaloids) or indirect (i.e., through the food web) effects on tadpoles. However, differences in survival were found. I suggest that large amounts of grass supplied excess organic matter that decomposed rapidly underwater, potentially causing a pulse of nutrients early in the larval period and anoxia. Wetlands invaded by reed canary grass may successfully produce metamorphs given that hydroperiods are adequate and eutrophic conditions do not occur in the wetland.