This thesis investigates the influence that cultural differences have in the designing of products and services that encourage sustainable lifestyles. This was researched through a case study of dishwashing practices in Mexico and the UK, and the development of a methodological framework for supporting designers working in cross-cultural contexts. Designers can shift user behaviour to be more responsible, and by doing this, reduce a product s impact on the use phase of its lifecycle. Nevertheless, designing products that successfully drive behaviour towards a more sustainable path can only be accomplished if they are conceived to fit the user and the specific context of interaction. In order to do so, designers must truly understand the users, and take into account the complex web of factors that lay behind individual behaviour. A comprehensive review of the literature established an understanding of human behaviour and the emergence and evolution of practices and routines. This brought to light the diverse behavioural patterns in different contexts; and was further investigated with a scoping study in two different locations (Mexico and the UK), exploring general water consuming practices in the home, specifically manual dishwashing practices. The preliminary findings shaped a study that aimed to deepen the understanding of these practices in the selected sites, involving the use of Cultural Probes and videoing people in their common kitchen environment. A robust and clear image of washing-up practices emerged with rich and detailed data presented in different media, ideal to be implemented in a design process. To this end, a series of multicultural Personas were created as the direct outcome of the Cultural Probes and the scoping study, giving way to the design studies phase of the project, carried out with industrial design students in Mexico and the UK. A design brief for sustainable washing up practices was delivered. Design experiments were used to provide interesting evidence of the influence in the design process of the designers understanding of the target user. The findings indicate that designers benefit from exploration and creativity tools tailored directly from the user-research findings in the early design process. This increases the level of empathy towards the user, particularly making it easier to design for users with different needs and contexts than the designers themselves. It also helps designers to better apply design for sustainable behaviour framework to their concept designs.