RESUMEN
This paper analyzes data from 1666 Spanish industrial firms to test how some human resource (HR) flexibility dimensions mediate the relationship between research and development (R&D) efforts and the absorptive capacity of knowledge (AC). The results show that external R&D experts and core employee training partially mediate the relationship between R&D effort and AC, whereas temporary employment does not mediate that relationship. These findings seem to suggest that HR flexibility dimensions that are more knowledge-intensive are more influential on the development of absorptive capabilities. Another finding is that the mediator effects of HR and AC are positively related to innovation performance, suggesting that firms may combine them more effectively with R&D efforts to enhance innovation.