Motivational interviewing is a counseling method used to bring about behavior change; its application by school nurses for preventing obesity in children is still new. This study, based on in-depth interviews with 12 school nurses, shows how school nurses adapted motivational interviewing and integrated it into their daily practice along with other methods they knew from the past. Three dilemmas for school nurses were revealed: when the child was severely overweight and the parents did not perceive this as a problem, when the child and the parents were at different stages of motivation to change, and when applying an individualized approach such as motivational interviewing for preventing a complex societal problem, in this instance obesity. The study raises an important issue to consider, with implications for school nursing and obesity prevention: motivational interviewing as either a counseling method or a prevention strategy.