This study investigates small firm internationalisation from an individual owner-manager’s perspective. Despite advancing our understanding of small firm internationalisation, process-based theories including the Uppsala, innovation-related and networks explanations, and more recently entrepreneurial-based theories remain vague in relation to what characterises and constitutes the internationalisation practices of small owner-managed firms. Process theories overlook the owner-manager and their practices, while entrepreneurial explanations focus on individual characteristics to the exclusion of their internationalisation practices. Furthermore, existing explanations are constrained by rationalistic assumptions prevalent in small firm internationalisation research which de-emphasise comprehensiveness, connectedness and complexity in favour of de-contextualised parsimonious causal relationships, thereby limiting investigations into how owner-managers understand and practice firm internationalisation. As a way forward, an alternative interpretive lens is adopted using a phenomenographic approach to explore how owner-managers understand and practise firm internationalisation. Consequently, the owner-manager’s lived experiences of firm internationalisation provide the point of departure for this study. In-depth interviews with owner-managers of small internationalising wineries, together with observations, field notes, documentation and secondary data formed the basis of my empirical material which was analysed in two-stages. The material was initially analysed in terms of what constituted firm internationalisation practice, and was subsequently examined to explore how owner-managers understand firm internationalisation. A small firm internationalisation activity cycle comprising: assessing and knowing markets, prospecting and attracting agent interest, assessing agent compatibility, supporting and sustaining agent relationships and termination or failure of agent relationships emerged as what constituted their internationalisation practice. Subsequent analysis revealed how owner-managers understood firm internationalisation by identifying four qualitatively different understandings of firm internationalisation practices: seeking market knowledge, competing on price, portraying distinctiveness and storytelling. The internationalisation activity cycle and the understandings of firm internationalisation were later connected to form an understanding-based theory of small firm internationalisation. This study contributes to small firm internationalisation theory in two ways: first, the articulation of an on-going and inter-connected internationalisation activity cycle of the small firm extends existing theories by providing a more complete and accurate explanation of how owner-managers of small firms conduct their internationalisation practices. It makes visible the activities, processes and relationships obscured by existing theories. The internationalisation activity cycle, through the inter-relatedness of each of the activities concurrently, combines market knowledge processes with processes of attracting, building and replacing network relationships with domestic and foreign-based actors. Second, revealing different understandings of internationalisation practices of small owner-managed firms, and associating these understandings of internationalisation with their internationalisation activity cycle not only extends existing theories but offers a new explanation of small firm internationalisation. An understanding-based theory of small firm internationalisation advocates that variations in conduct and activities undertaken by owner-managers are determined by their different understandings of firm internationalisation. As a result, owner-managers attach different meanings to the activities within the internationalisation activity cycle as they conduct their internationalisation practices. Consequently, the variability and idiosyncratic nature of small firm internationalisation is captured as one of multiplicity, rather than demanding universal explanation proposed by existing theories. Keywords: small firm, internationalisation, understanding-based theory, internationalisation activity cycle, phenomenography Australian and New Zealand Standard Research Classifications (ANZSRC): 150304 entrepreneurship 10%, 150308 international business 70%, 150314 small business management 20%