Environmental health is an extensive and intricate field focused on understanding how environmental factors interact with biological systems. Understanding environmental health is complex, encompassing the physical environment and social, economic, cultural, and political factors, all impacting human health. It requires a coordinated multidisciplinary approach to study and effectively address health outcomes influenced by the environment. The theory has long organized vital concepts and relationships to explain behaviors in health promotion, suggesting ways to expand its impact on population health by considering the increasingly complex social, cultural, and environmental factors influencing behaviors. Health behaviors are individuals’ actions that impact health and mortality, intentionally or unintentionally. They are dynamic, changing over time, across different groups, and throughout life. Health behaviors are pivotal in shaping individual and population health and well-being. They are multifaceted, influenced by various factors such as age, location, and societal structures, highlighting the interplay between personal choices and external influences. Health promotion, which has gained new prominence in recent years, focuses on positive health factors, addresses social determinants, and strives for health equity by redistributing power and resources. This chapter will explore the intersection of health behavior and health promotion theories within environmental sciences and health. It will examine applying theories such as the Health Belief Model, Transtheoretical Model, Social Cognitive Theory, Socio-Ecological Model, Theory of Reasoned Action, and PRECEDE–PROCEED Model to understanding and promoting health and health behavior within environmental contexts.