This paper investigates the determinants of punitive attitude toward cartels and it documents the factors underlying the support for harsher sanctions against cartels. The responses are collected in an experimental design in which respondents are exposed to various levels of cartel-type agreement costs. This experimental manipulation allows us to document the fact that individuals are more punitive towards cartels when they are victims of cartels that reduce substantially their earnings. In addition, punitiveness increases in the number of cartels experienced. Overall, punitive attitudes towards cartels are influenced by socio-demographic variables as higher ages, higher education level and being a man is associated with higher punitiveness attitudes. Behavioral dimensions such as the willingness to see firms involved in cartels punished or the perceived seriousness of cartels are associated with higher punitive attitudes.