Results indicate that the general developmental trajectories of positive and negative health-related behavior show an increase of positive and negative health-related behavior for the younger sample ranging from grades two to five. The older sample, ranging from grades four to seven was characterized by an increase in negative and a decrease in positive health-related behavior. Therefore, the focus of early interventions should be on early health-related behavior patterns (like nutrition, physical activity, etc.) as well as on variables related to these behavior patterns (like parenting styles). Most of the current prevention programs do not attempt to affect the perception, appraisal, or behavior of significant others like parents. The study also highlights the father's role in the development of health-enhancing or health-maintaining behavior in the transition from childhood to adolescence. An increase of negative health-related behavior and a decrease of positive health-related behavior may be normative; however, an early focus on health behavior and perceived parenting as a related influential variable could lead to a substantially reduced level of problematic health behavior and could be associated with substantial health promotion in later age groups. Data were collected from 2 samples: the first sample consisted of 432 students (grades 2 through 5), and 366 students (grades 4 through 7) in 15 German elementary schools of 1 administrative region. Tables, figures, and references