Inter-organizational cooperation is considered highly important for company success. While the concept of inter-organizational cooperation itself is well-established, the great potential of cooperation specifically with startups emerged over the last few years. Interestingly, even though there are strong motives for this specific kind of cooperation, researchers identified a lack of profound understanding and abilities of established companies in terms of interacting successfully with relevant startups. Drawing on resource complementarity as conceptual basis, we investigate how established companies can develop a generic approach to manage startup cooperation effectively and efficiently. In a first step as part of a broader research endeavor, this study identifies the difficulties lying in this kind of cooperation from the startup perspective. The results reveal the issues established companies need to solve in order to interact with startups in a productive way. A follow-up study will offer the necessary guidance for strategic decisions on startup cooperation initiatives and consequently enhance the chances of realizing the high expectations associated with startup cooperation.