This paper uses confidential Census longitudinal microdata to examine the association between R&D and productivity for the period 1972.1985. These data allow for significant improvements in measurement and model specification, yielding more precise estimates of the returns to R&D. Our results confirm the findings of existing studies: 1) positive returns to R&D investment 2) higher returns to company-financed research 3) a productivity "premium" on basic research These results are robust to our attempts to adjust for "influential" outliers. Also, it appears that the return to company-financed R&D (but not total R&D) is an increasing function of firm size.