A primer composition that provides a primer layer that improves adhesion between a coating and a substrate. The primer composition includes an adhesion promoter and a catalyst. The adhesion promoter includes a functional group that reacts with the substrate and a functional group that reacts with the coating or a component of the coating composition used to form the coating. Functional groups that react with the substrate include hydroxyl groups and alkoxy groups. The coating or components of the coating composition may include thiol or episulfide groups. Functional groups of the adhesion promoter that react with the coating or coating composition include epoxy groups and episulfide groups. The coating may form from a reaction between the coating composition and the primer layer and/or between components of the coating composition. The reaction that forms the coating may be catalyzed by a catalyst in the primer layer that was included in the primer composition.