Abstract. Based on the data from survey responses and publications of 1583 academic scientists in Spain, this paper examines the relationship between scientific performance and reward, considering tenure and permanent positions as key academic rewards in early phases of academic career and focusing especially on the mediating effect of mobile versus stable career paths. Although widely practiced, inbreeding has often been considered to be at odds with universalism and merit in science. Our findings indicate that inbred faculty does not get tenure with less scientific merits than PhDs from other institutions; we also find that non-mobile careers are a strong predictor of the timing of rewards in the form of early permanent positions. Our results question the assumption mainly based on US evidence that mobility enhances career. These findings must be interpreted in the context of organizational and institutional features of the Spanish academic system that promote the development of internal academic research job markets.