The engagement of independent experts or expert organizations in the process of delivery of public services and performing government functions is one of the most important form of public participation in the creation and/or implementation of public policy (creation of general principles as well as making specific decisions). It happens because of the lack of transparency in decision making of government agencies and lack of mechanisms of self-regulation. The article analyses current practices in engaging experts and organizations. The study is based on 250 administrative regalements of government functions and their projects. Authors study the models of interactions between the applicants, government agencies and organizations (experts). Moreover, authors study the relationship between the characteristics of the transaction on which the government function is based and the most preferable model of experts’ engaging for performance of the function.