We examine the influence of wildfire institutions on management and forest resilience over time, drawing on research from a multiownership, frequent-fire, coupled human and natural system (CHANS) in the eastern Cascades of Oregon, USA. We constructed social-ecological histories of the study area’s three main landowner groups (national forest, private corporate, and tribal) using a historical framework (1905–2010). Our findings highlight two infrequently recognized linkages of multiownership, frequent-fire CHANS: (1) informal institutions (e.g., cultural norms, knowledge system and fire paradigm) and institutional history often influence wildfire management adaptation (changes in forest fuel treatment, harvest fuel treatment, and wildfire incident response) through interactions with formal institutions (e.g., policy, law) and consequent effects on managers’ decision-making flexibility; (2) institutional interactions over time can influence forest resilience, thereby contributing to forest structural variation in multiownership landscapes. Consequently, the factors that contribute to maladaptive wildfire management are heterogeneously distributed across ownerships and the landscape. The timing of institutional dynamics also matters: manager flexibility to respond adaptively to wildfire hazard change seems to depend on synchronicity in evolution between informal and formal institutions, whereas asynchronous evolution (e.g., policy change, coupled with delayed shift in cultural norms or fire paradigms) may generate a time lag between unanticipated ecological feedbacks and management response. Thus, interventions that promote informal institutional evolution in tandem with developments in policy and law may shorten time lags, accelerating adaptation. A historical perspective can facilitate broad-scale, adaptive responses to wildfire-related ecological feedbacks in several ways: by providing insight into how informal institutions and institutional history interact with formal institutions to influence wildfire management behavior; by providing a historical baseline and system stages that contextualize current management behavior, ecological conditions, and policy options; and by illuminating historical sources of variation among ownerships and how they might be addressed.