Purpose – Considered that the boundaries between the firm and its surrounding environment are increasingly porous, allowing the use of both internal and external innovative ideas and commercial paths to create technological outcomes, this article aims to unveil both internal and external determinants of SME patenting. Design/methodology/approach – We propose an econometric approach based on a Hurdle Count Data Model which allowed us not only to overcome problems related to the count dependent variables often assuming zero values, but also to separate the willingness to patent from actual patenting. Originality/value – This methodology puts in evidence that an internal factor (i.e., human capital) significantly influences SMEs willingness to patent, while an external factor (i.e., collaboration with other firms) impacts on SME portfolio size. Differently from most studies in the area of IP management which adopt a macro level perspective and rely on secondary data (Candelin-Palmqvist et al., 2012), this paper assumes a firm-level approach and bases on primary data, which contributes to make it particularly distinctive. Practical implications – Results of our study highlight that SME innovativeness is positively influenced by human capital and external collaboration with other firms. Thus, human resource management could play an important role both in fostering employees’ awareness about IPR and their ability to exploit the knowledge they can acquire from external sources.