Clinicians are responsible for ensuring that their knowledge and skills are aligned with contemporary evidence and practice. This responsibility is reflected in the objectives of regulatory bodies such as the International Board of Lactation Consultant Examiners (IBLCE). However, there is no research evidence indicating what influences International Board Certified Lactation Consultants (IBCLCs) to continue to advance their practice. This study sought to address this gap in knowledge by investigating the IBCLCs perceptions of the structures and processes that influenced them in advancing their practice beyond initial certification. An interpretive approach was used to gain an in-depth understanding of the complex and contextualised interplay of the professional, cultural, personal, financial and other influential factors that affected the advancement of IBCLCs’ clinical practice. Donabedian’s structure–process–outcome conceptual model was used to guide the study. Exploratory sequential, mixed methods case study and qualitative– quantitative studies were conducted in two phases. Phase 1 comprised two pilot interviews, six focus groups of 37 IBCLCs from 10 different countries and seven staff interviews; the analysis involved thematic analysis. Phase 2 was an online questionnaire survey with fixed choice and open-ended questions, which was piloted and then emailed to 26,173 IBCLCs from 94 countries; the data were analysed using descriptive statistics and content analysis.