Regardless efforts by the (municipal) public health sector, public health still faces major problems. The involvement of other policy sectors is generally assumed as necessary. Because, in contrast to the public health sector, they have policy instruments to address the environmental determinants of health. The idea is that intersectoral policy networks will be established and integrated public health policy (IPHP) will be developed. IPHP is assessed as promising, due to the integration of health considerations into policies of non-public health sectors, i.e., in policy networks across portfolio boundaries. However, there is a lack of empirical evidence on the conditions under which these assumptions about IPHP are true. This study provides insights in the empirical manifestations of IPHP and the conditions under which IPHP leads to an integrated policy output in terms of addressing environmental determinants of health with multiple intervention strategies, policy innovation and perceived public health gain. We concluded that network intersectorality mattered to a certain extent and under specific conditions and that other conditions were also important. Such as the execution of network management strategies, horizontal network integration, a broad policy approach, the involvement of implementing actors in the policy development phase, a project leader from a non-public health sector. There is not one road leading to Rome, but various possibilities and combinations of conditions lead to an integrated policy output. When keeping such nuances in mind, possibilities arise for the realization of policy networks across portfolio boundaries in which an integrated policy output can be realized with IPHP.