In this paper we examine the moderating affect of age on the relationship between cooperation and new product success for entrepreneurial firms in the high technology region in and round Jena in the former East Germany. Cooperative strategy has already been shown in a variety of research settings to be an important strategic alternative for entrepreneurial firms to support growth strategies. We develop hypotheses that such cooperative relationships will also lead to higher new product development success; however, the type of successful cooperation will vary with the age of the start-up firm. Younger firms are shown to be more successful when they cooperate with other firms, while older firms will profit more from cooperation with research institutions. This study adds to a growing literature on the importance of cooperative strategy for entrepreneurial firms. (c) 2005 Elsevier Ltd. All rights reserved.