Using returns to scale as a conceptual foundation, we explore how R&D-related earnings performance and earnings variability depend upon firm size. We find that the positive association between the level of future earnings and R&D intensity increases with firm size, and that the positive association between the volatility of future earnings and R&D intensity decreases with firm size, consistent with R&D productivity increasing with scale. We also show that R&D scale is associated with lower market returns, consistent with the idea that R&D investment risk declines with scale.