We modeled development in grape berry moth, Endopiza viteana (Clemens), which exploits wild and cultivated Vitis. Laboratory experiments were used to derive the temperature-dependent developmental curve for eggs, larvae, and pupae. We used linear interpolation to estimate stage-specific base temperature thresholds and degree-day requirements under laboratory conditions. We also estimated parameters of the Logan and Lactin nonlinear developmental models. Lastly, we conducted field experiments to evaluate the conventional degree-day model, which has a base threshold of 10°C; an improved degree-day model that was based on our laboratory observations; and nonlinear developmental models in predicting seasonal grape berry moth development. We concluded that the Logan nonlinear model provided the best estimates of grape berry moth field development, and an improved degree-day model should use 8.41°C as a minimum base temperature threshold and 423.9 as the egg-to-adult degree-day requirement. Also, after comparing degree-day accumulation estimates using the maximum-minimum method and trapezoidal integration to hourly temperature measurements, we concluded that the two approaches provided similar estimates during June–September.