This article contributes to the literature on knowledge transfer via labor mobility by providing new evidence regarding the role of educational diversity in knowledge transfer. In tracing worker flows between firms in Denmark over the period 1995–2005, we find that knowledge carried by workers who have been previously exposed to educationally diverse workforces significantly increases the productivity of the hiring firms. Several extensions of our baseline specification support this finding and confirm that our variable of interest affects the arrival firm's performance mainly through the knowledge transfer channel.