Objective: To use a qualitative exploration to evaluate whether "Something to Smile About" (STSA), an oral health intervention, had increased the oral health capacity of staff working with homeless people. Setting: A National Health Service board area in Scotland. Method: A purposive sample of 14 staff members from STSA-participating organizations took part in the evaluation. Three focus groups were held and the participants were encouraged to speak freely about their views on the intervention. The qualitative data was analyzed using content analysis. Results: The majority of participants stated they were able to use their newly-acquired oral health knowledge and pass it to their homeless clients. STSA appeared to be less successful with regard to assisting clients to change their oral health behaviours. Staff felt that oral health considerations were a low priority compared to the need for shelter, food, clothing and money. In addition, they stated that the level of success with clients was influenced by the homeless person’s specific and complex needs. Conclusion: STSA was successful in building staff oral health capacity; however, for STSA to be successful with clients, and for clients to achieve adherence with oral health messages, the complex needs and current life circumstances of homeless client groups must be incorporated into STSA. (Contains 1 table and 1 figure.)