Social marketing, the use of marketing to design and implement programs to promote socially beneficial behavior change, has grown in popularity and usage within the public health community. Despite this growth, many public health professionals have an incomplete understanding of the field. To advance current knowledge, we provide a practical definition and discuss the conceptual underpinnings of social marketing. We then describe several case studies to illustrate social marketing's application in public health and discuss challenges that inhibit the effective and efficient use of social marketing in public health. Finally, we reflect on future developments in the field. Our aim is practical: to enhance public health professionals' knowledge of the key elements of social marketing and how social marketing may be used to plan public health interventions.