The present study aimed to determine extension requirements for slow food (SF) and to provide a model for SF extension in Iran condition. The study employed the systematic approach of grounded theory for model development. The statistical population was composed of all key experts of SF extension of which 15 individuals were selected as the sample by the purposive sampling technique. Data were collected by semi-structured interview method and analyzed by the systematic approach of grounded theory through the three stages of open, axial, and selective coding. The reliability of the findings was checked by members matching and peer review. For members matching, four participants of the final report reviewed the first stage of analysis and the derived categories. The results of the analysis showed that 169 initial codes derived at the first stage of open coding were narrowed to 37 codes and were finally grouped into six categories. It was tried in the research to use SF extension experts’ views to answer the question as to how a model can be presented for SF extension by grounded theory. This model is based on a rational pattern that includes the causes and factors underpinning SF, contexts, supporting conditions in the SF model, strategies, and consequences of people’s lack of tendency towards developing an SF-based lifestyle. People’s awareness and knowledge were emphasized by both previous research and the experts interviewed here. The results show that people’s participation in decision-making has a significant impact on the SF model and all individual citizens should be covered by the training programs to reach sustainable food diets.