Previous studies have identified regulatory preemption and differentiation as two main motives for participation in voluntary environmental programs (VEPs). This research examines the motivations of livestock farmers to participate in the Michigan Agricultural Environmental Assurance Program (MAEAP). It employs a signaling model of interaction between the regulator and livestock farmers under imperfect information to analyze the potential equilibria of participation decisions in VEPs. Data from a survey of livestock farmers in Michigan is analyzed to test hypotheses regarding the realized equilibrium in MAEAP participation. The results suggest that livestock farmers who are interested in regulatory preemption are more likely to be MAEAP-verified while those who are interested in differentiation are less likely to be verified at the time of the survey. Consistent with the model predictions under the regulatory preemption equilibrium, MAEAP-certified farms also perceived more stringent enforcement effort by the regulators.