Researchers have investigated the factors that influence environmental behavior for decades. Two often-investigated phenomena, connectedness to nature and self-efficacy, often correlate with environmental behavior, yet researchers rarely analyze those correlations along with underlying cultural factors. We suggest that this is a substantial oversight and hypothesize that cultural factors affect environmental behavior, particularly through an interplay with the connectedness to nature and self-efficacy constructs. To test this hypothesis, we surveyed eighth-grade students on the island of Hawai'i. The instrument included items to assess connectedness to nature and self-efficacy (both frequently measured in environmental behavior studies) and multiple measures of behavior. Most of the behavior measures are commonly used in studies of environmental behavior, and one was developed in collaboration with local partners to reflect more culturally specific modes of environmental behavior. With those partners, we also developed a construct reflecting the relevance of local culture. We explored the relative influence of the more commonly investigated constructs (connectedness to nature, behavioral variables) along with the newer construct (cultural relevance). We found that, when we took those considerations into account, cultural relevance significantly predicted connectedness to nature, self-efficacy, and a commonly used behavioral measure. Our results thus suggest that many models of environmental behavior may be misspecified when they omit critical culture- and ethnicity-related factors. This may be particularly important in contexts with high cultural, racial, and ethnic diversity or in contexts where mainstream Western environmental approaches are non-dominant. Our results emphasize the importance of addressing ethnicity and culture in environmental thought and action.