A national survey was developed in a representative sample of the Spanish population (15 years old and upwards). This study belongs to a partnership in a pan-European survey about stages of dietary change where subjects were classified into six different categories according to their readiness for dietary change: precontemplation (not considering any changes), contemplation (considering changes), decision (making plans to change), action (carrying out the changes), maintenance (maintaining changes for more than six months) and relapse stage (reverting back to eating less healthily). The main objective was to investigate the distribution of the different stages of change concerning dietary habits across strata of socio-demographic variables (sex, age, educational level, socioeconomic level). Also, this study was conducted to assess the relationships between stages of dietary change and the influences on food choice as well as the definitions used to describe healthy eating. The survey was carried out, according to an established protocol, on a representative sample of 1009 Spanish subjects selected by an at random multistage procedure. Subjects completed a face-to-face interview-assisted questionnaire. To ensure representativeness data were weighted by population size, by sex, age and regional distribution. The proportion of subjects in precontemplation (56.0%) and maintenance (28.3%) stages was substantially larger than in the other stages of dietary change. More males (59.7%) and subjects from the oldest age groups (65.8%) were classified as belonging to the precontemplation stage, while more females (30.2%) and subjects between 25-34 years of age (34.5%) were in the maintenance stage. 'Trying to eat healthy' as an influence on food choice was more frequently mentioned by those in the dynamic and maintenance stages, while a high percentage of subjects from the precontemplation and relapse stages (61.1%) agreed they did not need to make changes to their diets because their diet was already sufficiently healthy. A very high proportion of the Spanish adult population do not contemplate a change in their dietary habits. Intervention strategies in health promotion programs should be available for people at the various stages of change. It would be more effective to attempt to increase people's awareness and personal concerns about nutrition and health, before introducing action strategies.The adult population can be classified into different stages of dietary change, so the stages of change model may be applied to future nutrition interventions. This approach will help to focus more accurately strategies of nutrition education.