In this paper, we first estimate firms' total factor productivity by differentiating marginal contributions to firms' production from various types of workers, grouped by their highest educational attainments. Second, we investigate whether there are human capital as well as research and development (R&D) spillovers across firms. Using data for 72 Taiwanese high-tech firms, we find (a) more educated workers are more productive: workers with master's (bachelor's) degrees are at least three times (two times) as productive as high school-graduated ones, (b) human capital and R&D spillovers are substantial across firms, and (iii) smaller firms tend to benefit more from R&D spillovers. (JEL D24, I21, O3)