Social identity is valuable for studying social behavior because identical actions can have dramatically different meanings when viewed through the schemas and goals activated by membership in different social groups. The motivations to think positively about ourselves, our groups, and to cultivate warm social reactions drive us to behave in ways that demonstrate positive identities. Public behaviors are especially impactful on social status and self-perceptions, so the visibility of behaviors is a fundamental contextual feature that binds behavior more closely to identity. When public behaviors signal a desired social identity, individuals will be motivated to increase those behaviors relative to less visible actions. When public behaviors signal an unwanted social identity, individuals will decrease those behaviors relative to less visible actions. This claim is evaluated in the context of environmental identity and behavior in three United States surveys using ideographic sampling and multilevel modeling to incorporate variability in how behaviors are viewed (Chapter 2, N = 1,126), and three laboratory experiments manipulating visibility and objectively observing environmental behavior (Chapter 3, N = 735). Strong support was found in the correlational studies for the moderation of visibility on the relationship between identity and behavior, controlling for a wide range of confounds. The experiments successfully developed a convincing context where individual identity predicted environmental behavior, but were inconclusive for testing for moderation by visibility. Theoretical and methodological advances are described for both social psychology and environmental psychology, and future designs and suggestions for research are provided (Chapter 4).