We examined the influence of plant genotype and early-season water deficits on oviposition preference and several measures of offspring performance in the goldenrod ball gallmaker (Eurosta solidaginis). Replicates of eight genotypes of goldenrod (Solidago altissima; Asteraceae), subjected to one of two watering regimes, were exposed to mass-released E. solidaginis. Oviposition preference was significantly affected by plant genotype and early-season water deficits, but not by their interaction; generally fewer plants in the low-water regime than the control treatment were ovipunctured in the first 24 h. In contrast, the number of ovipunctured plants forming galls was significantly affected by plant genotype and the interaction between plant genotype and early-season water deficits. Only plant genotype significantly affected the mass of adult offspring, which was highly correlated with potential fecundity in females. In the genotypes examined, oviposition preference was not affected by the interaction between plant genotype and early-season water deficits, but gall formation was. These results demonstrate the importance that the interaction between plant genotype and early-season water deficits can have on gall formation in E. solidaginis, and suggest that ovipositing females may be selecting hosts based on a subset of the traits that influence offspring performance.