The Groningen Overweight and Lifestyle (GOAL) intervention effectively prevents weight gain. The present study describes a process evaluation in which 214 participants in the intervention group received a structured questionnaire within 7 months (a median of 5 months) after the end of the intervention. The authors investigated the content of the intervention (on basis of the participants' recall), the participants' satisfaction of the intervention, the participants' satisfaction with the nurse practitioners (NPs), and the determinants of the participants' satisfaction. In general, the results show that the content corresponded well with the protocol for the intervention, except for the number of telephone calls and the percentage of participants with individualized goals for a healthy lifestyle. The overall satisfaction of the participants was high, and success and perceived success and a low educational level were important determinants for a higher overall satisfaction grade. Furthermore, the NP was considered to be an expert and motivational to learning and keeping up a healthy lifestyle. The authors therefore conclude that the GOAL study is feasible and indicates that the NP is well equipped to treat these patients. However, it is recommended to reinforce the advice given and the lifestyle goals after the first contact sessions. (Contains 5 tables.)