The aim of this thesis is to identify and examine the factors influencing environmentally-significant consumption (ESC) by higher-income households (HIH) to provide theoretical and social marketing insights. Income is highly related to levels of energy consumption and associated environmental damage, but despite research documenting the links between income and energy use, there is a lack of enquiry into what shapes the ESC patterns of HIH and therefore how behavioural interventions might be best fashioned to reduce energy use. A postmodern approach to consumption that recognises the interplay between the psychological, the social and the cultural (a psycho-socio-cultural approach), indicates that ESC is not an automatic consequence of wealth but rather mediated through the way consumption practices are symbolically connected with the satisfaction of underlying needs, including the need for identity and other psychological orientations. These connections are not universal or static but socially and culturally contextual and influenced by many factors, particularly marketing. Social marketing, as marketing for social good, therefore has a critical role to play in altering these symbolic connections and therefore consumption behaviour. To design and market alternative lower energy consumption through social marketing interventions, an understanding of how environmentally-significant consumption is connected with modes of need satisfaction and psychological orientations is necessary. Additionally, an understanding of constraints to even higher levels of consumption is useful. This study provides initial research momentum, using a HIH sample from South Devon. Primary data from a quantitative questionnaire was supported in design by qualitative interviews. These provide descriptive and correlational results about what shapes the consumption of; leisure flights, large-engine cars and new durable products, as well as the role of environmentally-significant psychological orientations, specifically: values; materialism; environmental concern and identity. The research also provides a comparative analysis between a group of HIH who have participated in Global Action Plan’s EcoTeam programme, and the general sample of HIH.