Based on the theory that a positive environment meets human needs whilst at the same time it stimulates engagement in environmentally protective behaviours, this study empirically tested a model of family positivity, considering the responses given by 200 Mexican interviewees in a research survey. In the model, a series of positive characteristics pertaining to the home (privacy, pleasant temperature, lack of noise, cleanliness) constituted a positive physical environmental factor for the family, whereas positive social family atmosphere comprised indicators of affection and intimacy and a democratic style of relations between the members. The model also included a factor pertaining to sustainable behaviours, created through the reporting of pro-environmental, frugal, altruistic and equitable behaviours. The positive physical and social factors of the family environment produced a second-order factor, identified as 'Positive family environment'. This secondorder construct was saliently and significantly associated with the sustainable behaviour factor, providing empirical support to the theoretical model of environmental positivity in the family.