The environmental impact of food consumption depends on the type of foods consumed and the amount of food wasted. It follows that dietary change represents one means of directing food systems towards greater environmental sustainability. The difficulty, however, lies in developing ways of motivating people to modify what they purchase and eat, as many constraints potentially hinder changes in behaviour, including established habits, limited income, lack of information on environmental impact, cognitive limitations, or the difficulty of accessing environmentally friendly foods. In order to understand those constraints better, and identify potential target groups for intervention, we have analysed the environmental impact of food consumption at household level in Finland, paying particular attention to lower socio-demographic groups. The data originates from the Finnish Household Budget Survey 2006, which gives a detailed record of the foods (259 aggregates) consumed by over 4000 households. The food quantity data are matched to indicators of greenhouse gas emissions and eutrophication, as well as a food composition database. Tests of differences in means of the environmental indicators identify the socio-demographic groups that are statistically different in terms of their environmental impact of food consumption. The total environmental impact is decomposed further into a diet composition effect (i.e., what foods households consume) and a quantity effect (i.e., how much food households consume). Results indicate that the environmental impact varies widely across households, and that this heterogeneity relates both to the types and quantities of foods consumed. We find significant differences in impacts among socio-demographic groups. For instance, household income is strongly and positively associated with greenhouse gas emissions from food consumption (i.e., relatively better off households have a relatively larger climate change impact). Educational level is also positively associated with greenhouse gas emissions, although the relationship is not as strong as with income. On the other hand, differences in environmental impact for household types defined in terms of occupational status are small. Overall, and on the basis of the two indicators considered, the lower socio-demographic groups have a relatively smaller ecological footprint of food consumption than households belonging to relatively higher groups. The results suggest that there is no decoupling of household income growth and environmental impact of food consumption. The relatively better-off and better educated should be targeted for behavioural change in order to promote sustainable food consumption in Finland. Further research is needed to identify the causal mechanisms underlying the associations that we describe and assess how various policies (e.g., labelling regulation, environmental education) would affect the ecological footprint of the Finnish diet.