This paper examines the use of alliances between technology start-ups and established firms. The topic is of interest as it is well documented that technology start-ups can drive economic growth by playing a significant role in the process of innovation, i.e., the successful exploitation of new ideas. However, technology start-ups face numerous challenges in bringing their technologies to market, many of which are related to the problems accessing the complementary assets needed to support the exploitation of their core competence(s). Alliances with larger firms that possess the complementary assets (e.g., production capability, distribution channels, etc.) lacking in the start-up would seem to be an attractive option for supporting the growth of the start-up. Yet research shows that such alliances can be problematic to setup and manage, and can actually be harmful to the performance of the start-up. This paper draws on evidence from eight case studies of start-ups based in Cambridge, U.K., and applies a resource-based framework to help structure our understanding of (1) why these alliances are so challenging, (2) what benefits (both intended and emergent) can be derived from them,  and (3) to propose a structure for underpinning improvements in the process of setting-up and managing such alliances.