The purpose of this investigation was to evaluate the effects of nutrition health intervention on pupils' nutrition knowledge and eating habits from grade seven to grade nine. The study was part of the ENHPS (since 2008, Schools for Health in Europe (SHE)) program in Finland, and more specifically its sub-project titled "From Puijo to the World with Health Lunch." This study was conducted among the pupils of two experimental schools and two control schools by means of a paper questionnaire. The results show that the experimental school pupils' knowledge of nutrition increased positively during the intervention. Furthermore, the pupils of the experimental schools were found to improve their eating habits and eat school lunch on a more regular basis during the intervention than the control school pupils. (Contains 2 figures and 3 tables.)