Business Incubators (BIs) play a key role in the growth and support of technology-based startups. They are an important driving force of innovation. Although, a significant amount of research efforts has been paid on the outcome and benefits of business incubators, there is still a scarcity of studies on the role of business incubators in empowering technology-based startups and making them a success. The current paper aims to address this inconclusiveness. As a first step, it explores the supportive activities offered by business incubators. For our research, we use data from eleven interviews with founders of high-tech startups, who received the support of public incubators. Our research methodology follows grounded theory to code and categorize the data. The first result shows the classification of supportive activities of BIs into five categories: (1) networking, (2) monitoring, (3) knowledge development, (4), resource mobilization, and (5) creation of exposure. As a second result, we map the interrelations between the identified activities, and present our conceptual framework. The framework can be considered as a tool to measure the effectiveness of BIs' activities on New Technology-Based Firms (NTBFs). It is illustrated by exploring five propositions. The paper contributes to the development of incubators, and incubator-incubatee impact studies through the lens of resource-based theory. It concludes with recommendations for researchers and practitioners.