Public engagement is increasingly advocated and applied in the development and implementation of technological innovations. However, initiatives so far are rarely considered effective. There is a need for more methodological rigor and insight into conducive conditions. The authors developed an evaluative framework and assessed accordingly the effectiveness of a project of the Dutch Ministry of Health, Welfare and Sport in which the application of interactive policy making was piloted in medical biotechnology, among others, to increase the legitimacy and quality of the policy agenda. Relevant societal actors, including citizens, were actively involved in an open-exchange, action and reflection process, integrating relevant knowledge. Although the project was overall evaluated as effective, some difficulties were faced. These were mostly related to the novel roles public engagement requires of principal actors. The article concludes that more research is needed on the position of the executing team and on overcoming tensions existing between different governance modes. (Contains 1 figure, 4 tables, and 5 notes.)