Using survey data from 1438 Peruvian manufacturing firms, we explore multiple and simultaneous relationships between the effects of innovation activities, employee level of education, and the firm size on manufacturing firms’ innovation outcomes. We find that there is a positive relationship between innovation activities, employee level of education, and firm size. In addition, innovation activities have direct and positive effects on product and service innovation. However, employee level of education has positive indirect effects, especially on product innovation. The study also highlights that there is a negative direct relationship between size and service innovation. Thus, it is important to establish public policies aimed to promote service innovation in manufacturing firms, with specific support for small firms.