Entrepreneurial teams in research-based spin-off companies face specific constraints for establishing sustainable ventures. They often lack managerial and entrepreneurial skills, because the scientists themselves are typically the founders and managers. For this reason, the compositions of the entrepreneurial teams are likely to change over time and involve experienced external entrepreneurs and managers (Franklin et al., 2001; Vanaelst et al., 2006). This study analyzes the characteristics and compositions of executive teams in research-based spin-offs. Drawing on an upper echelons framework (Hambrick and Mason, 1984) executives´ prior professional experiences are expected to have an essential impact on organizational outcomes such as strategy and performance. According to effectuation and causation theory (Sarasvathy, 2001) experienced entrepreneurs are more likely to rely on intuitive reasoning, whereas entrepreneurs without prior experiences presumably tend to plan more systematically and analytically.