Social exclusion related to the unemployment of vulnerable population groups constitutes a crucial limitation to achieving a sustainable world. In particular, young and senior populations have specific characteristics that put them at risk of exclusion from the labor market. This circumstance has motivated an attempt to foster cooperation between these age groups to enable them to develop entrepreneurial initiatives that will contribute to close this social vulnerability gap. We approach this topic by focusing on intergenerational entrepreneurship, understood as entrepreneuring projects jointly undertaken by seniors and young adults. The objective of this study was to identify the differences and complementarities between senior and young entrepreneurs with a view to enabling them to develop viable intergenerational entrepreneurial projects, with special emphasis in the motivational push, pull, and blocking factors that affect them. This kind of entrepreneurial initiative fosters knowledge transfer and experience between age groups, promotes job creation and social inclusion, improves a sense of belonging, and, thus, contributes to the construction of a stronger society serving as an engine for sustainable development. Therefore, intergenerational entrepreneurship can be considered a form of social innovation. A mixed-methods approach was utilized in this study, using quantitative data from a questionnaire as a starting point for the characterization and identification of senior and young entrepreneurial profiles, and qualitative data from focus groups, which enabled us to identify complementarities among generations. The results show that there are significant differences between youths and seniors in terms of the motivations and factors that push, pull, or block the decision to form an intergenerational entrepreneurial partnership. These differences can be interpreted as complementarities that can boost intergenerational cooperation to promote social inclusion.