Recent evidence has shown that entrants into entrepreneurship are disproportionately drawn from the population of high ability employees who are exposed to entrepreneurial environments. This paper utilizes register data to examine the origins of such an ability–the exposure effect. Military conscription records for 25,000 Swedish men allow us to investigate the importance of general and social ability, measured at age 18. Evidence suggests that employees with lower ability are more strongly affected by entrepreneurial environments than those with high ability.