Mayne SL, et al. - Researchers utilized data from the 2011–2016 National Health and Nutrition Examination Survey, to provide information regarding the co-occurrence of unhealthy behaviors within individual children across childhood and adolescence. Among US children and adolescents (n = 7,714), stratified by age group (2–5, 6–11, 12–15, and 16–19 years), the weighted prevalence of unhealthy behaviors, including excessive screen time, poor diet quality, low physical activity, fast food consumption, and smoking (adolescents only), was calculated alone and in combination. In this study, excessive screen time and poor diet quality emerged as the most prevalent behaviors. With age, a significant rise in unhealthy behavior clustering was seen. A low prevalence of smoking was reported, but ≥ 1 other unhealthy behavior was noted in 97% of smokers. Black vs white children (ages 2–5 and 6–11) exhibited significantly more prevalence of unhealthy behavior clustering, while it was less prevalent among Hispanic older adolescents (age 16–19). Links with household features differed by age group. Concerning the extent of co-occurrence of unhealthy behaviors in US children and adolescents, population-level knowledge is offered by the findings.