Abstract:  Maternal effects are the non-genetic influence a mother has on her offspring’s phenotype and can influence the way an organism responds to natural selection.  Maternal effects have been demonstrated in several species using a cross-fostering design which involves the switching of eggs between pairs of mothers.  This study was designed to determine the specific maternal effects on hatchling size in Plethodon cinereus, a salamander conducive to cross-fostering experiments because it demonstrates maternal care on a small clutch size.  It has been found that large females tend to produce offspring larger than anticipated based on oocyte size, so the correlation of maternal body size with egg size was examined.  Gravid females were captured and induced to lay, then their clutches were switched within pairs of various size differences and brooding behavior observed. Various egg characteristics were compared with both foster and genetic mother’s body size using a multiple regression analysis.  Egg volume was significantly correlated to the genetic mother after egg development but not prior to oviposition, suggesting that an internal factor such as high quality yolk or genetics play a role in increasing egg size.  The residuals of egg volume on egg mass, a measurement of density, were significantly correlated to the foster mother, possibly as a function of better hydration of eggs on the part of the brooding mother.  It was shown that higher hydration leads to higher egg mass.  No conclusion could be drawn on the behavioral data to explain why larger females are able to generate denser eggs.  Differences were seen in the variation  of brooding behavior between the cross-fostered and control females, suggesting that in this experiment treatment did have an effect.