In most industries, innovation has become the most critical success factor to compete: thanks to the rapid change in technology, shortened product lifecycles and market globalization, executives' focus on new product development activities has become even more stronger. On the one hand, the simultaneous effect of (external) supplier and (internal) purchasing involvement into NPD has seldom been tested, and the great part of relevant studies is based on case studies rather than large - scale surveys. On the other, scholars' recommendations are sometimes contradictory, with authors exalting benefits of supplier involvement, while others remarking its criticalities. Within this scenario, the present work aims to investigate the role of supplier and purchasing department onto the firm generation of innovation at the category level; a consistent theoretical framework has been designed and tested using data collected from a survey including 603 companies worldwide.