The goal of the Ulcus Cruris Care project is to enhance the primary care provided to patients with venous leg ulcers (VLUs) in General Practitioner (GP) clinics through the implementation of a multifaceted intervention including educational materials, standardized treatment recommendations, computerized documentation, and case management by non-physician medical assistants (MAs). The current outpatient treatment of VLU patients and associated implementation determinants were thoroughly explored before the intervention components were implemented and tested in general practices. In order to identify potential implementation determinants, a mixed-methods study examined the perspectives of GPs, MAs, and patients about the current VLU outpatient service and the anticipated intervention components. About 2  different methods were used to compile this data: a survey questionnaire (n=28) and semi-structured guide-based telephone interviews (n=29). Transcripts of interviews were taken word for word. To aid in structuring important implementation factors, inductive analysis was performed first before transitioning to a deductive-inductive strategy based on domains of the Theoretical Domains Framework. Analysis of the survey data was done descriptively. Currently, outpatient care at VLUs is frequently individualized based on the wounds and gradients of each patient. General practitioners (diagnostics, counseling) and MAs shared patient loads (wound care). Although all medical professionals were aware of compression therapy, not all saw it as a crucial part of VLU treatment. As standardized operating processes, E-learning and other forms of distance education were viewed as a plus. Care at VLUs could be improved with the help of stronger participation of non-physician assistants. The use of standard operating procedures and the incorporation of software-supported case management into everyday practice have been noted as areas of concern. The results of this study highlighted the importance of educating both VLU care professionals and patients about the benefits of compression therapy. The conceptualization of the proposed intervention seems acceptable, and structured guideline-based case management might be a feasible way to optimize VLU treatment.