Background Post mastectomy breast reconstruction is an elective procedure offered to women as part of surgical treatment for breast cancer. Choosing to have a reconstruction, or not, and when, is a timely and challenging decision for women in an emotive environment. Decision support interventions (DSIs) have proved beneficial in enabling decision making with patients and clinicians in similar situations of clinical equipoise. The goal of the DSI is to facilitate a decision that is reflective of the patient's own priorities and preferences. However, the implementation of DSIs into routine clinical practice has proved challenging. The thesis reports on the development of a post mastectomy breast reconstruction DSI and on the feasibility of implementing a DSI in the clinical environment. Methods Women's decision making about breast reconstruction was examined through a literature review and a thematic analysis of interviews with breast cancer survivors. A collaborative development framework and iterative process were utilised to design the breast reconstruction DSI. The breast reconstruction DSI was introduced into the clinical environment in a feasibility study to identify potential barriers and facilitators to implementation. A case study approach, including the decisional conflict scale and qualitative methods, examined the perceptions and experience of the patients and clinicians using the DSI in a breast cancer clinic. Results The Option Grid DSI was published on-line as part of the Option Grid Collaborative. In feasibility testing, its flexibility and accessibility were positive features in terms of its implementation. The content and format facilitated the comparison of options. The timing of when it was introduced impacted its effect on patient decision making. Conclusions The support of local stakeholders was significant in the development of the DSI. The Option Grid DSI can be integrated into routine clinical practice, and gave some consultations more structure. Patient participants in the feasibility study found it constructive in facilitating their decision making. Further testing to explore the timing of the DSI and its impact on a wider audience is warranted.