Health literacy has traditionally been conceptualised as individual skills in a health context. Although there is growing consensus that health literacy is a multidimensional construct, interacting with socio-cultural contextual influences, such aspects are under-researched. In particular, there is limited research regarding the interrelationships between individuals’ and primary healthcare professionals’ (PHCPs) health literacy beliefs and experiences. Despite the predicted impact of the ageing population on healthcare costs and services, little empirical research has been conducted in New Zealand (NZ) on the health-related behaviour of the influential baby boomer cohort. The purpose of this thesis is to explore the phenomenon of health literacy among NZ baby boomers and PHCPs. Using hermeneutics as both the theoretical lens and the research method, this research draws on in-depth interviews to understand the participants’ constructions of health literacy and how their constructions influence healthcare goals and service encounters. The research takes a broad perspective of health literacy to answer the overarching research question, How are the roles and practices of health literacy perceived/constructed and performed in primary healthcare? This thesis makes an original contribution to knowledge as the first empirical investigation of health literacy of NZ baby boomers (46 participants) and NZ primary healthcare professionals (11 participants). Specifically, this research contributes to health literacy knowledge in a geographic area (NZ) and among individuals within a generational cohort not defined by health condition or health risk. NZ baby boomers construct health literacy as a highly contextualised social practice linked to [a]symmetries in health-related information, power, autonomy, and patient-practitioner roles. These participants stress the importance of an individual’s personal health context, capabilities, relational processes, and networks in health literacy. Interpreting these baby boomers’ health literacy behaviours leads to five categories of description - seeker, decider, networker, sensemaker, and manager, which are appropriately framed within two horizons of self and interactivity, providing conceptual space within which individuals move and adapt their health literacy roles, responsibilities, and behaviours. In the PHCPs’ experiences regarding baby boomers’ health literacy there are underlying power and information imbalances, conflicting authority concerns, and [de-]professionalisation issues. Using categories of description, the PHCPs’ health literacy behaviours are described as – knowledge broker, ethical agent, and enabler. Iteratively drawing on pre-understandings, these meanings are theorised in a collective notion of managed empowerment that implies a negotiated balance between PHCP expert control and professional expertise, and patient-consumer autonomy and expertise. This study extends the understanding of health literacy by presenting an empirically-based conceptual framework, depicting health literacy operating across multiple levels, relationships, and networks, variably influenced by contextual factors of the postmodern health context; the communication and information revolution; and neo-liberalism and consumerism. The thesis contributes to health literacy knowledge by illustrating the fundamental role of relational processes in co-producing individuals’ health literacy and in subsequently reaching individuals’ health goals. Primary healthcare service providers, policy makers, and health promotion advocates can benefit from this study as it reveals particular health literacy roles and behaviours likely to be influential in encouraging individuals’ authentic involvement in their healthcare.