Background: Policy, systems and environmental (PSE) approaches can sustainably improve opportunities for healthy eating (HE) and active transportation (AT). PSEs require cross-sector collaboration. Adopting and implementing PSEs is complex and not well understood. Methods: First, using a national probability survey dataset of US local health departments (LHD), inclusion of HE and AT PSE strategies in local community health improvement plans (CHIPs) was examined. Next, a content analysis of current CHIP documents provided data for multilevel latent class analyses to identify classes of CHIPs based on patterns of PSE-strategy alignment with six key activities that facilitate change. Lastly, semi-structured interviews informed a qualitative exploration of early stage Complete Streets policy implementation in Worcester, Massachusetts. Results: Less than half of US LHDs reported developing a CHIP containing any HE policy (32%) or AT (46%) strategies. Two classes of CHIPs were identified: CHIPs in Class A (HE: 71%; Physical Activity (PA): 79%) simply identified a PSE solution; Class B CHIPs (HE: 29%; PA 21%) mostly included PSE strategies that comprehensively addressed multiple key activities. Six themes emerged as factors for early Complete Streets implementation. Conclusions: This mixed methods study provides a novel understanding of the status, development and implementation of PSE strategies in relation to collaborative strategic health improvement planning efforts. CHIPs are underutilized to promote PSE strategies and few CHIPs in our study developed strategies that comprehensively address the process of PSE-change. Among other factors, CHIPs may provide a guiding structure for policy adoption and implementation.