This article presents a mixed-method study utilizing teacher ratings of principal mindfulness from 149 public schools in Texas and follow-up qualitative data analysis through semi-structured interviews conducted with the top 10 percent of princeipals identified as mindful. This research is based on the theoretical framework of mindfulness as established by Langer, refined by Weick and Sutcliff and applied to school settings by Hoy. For the quantitative methodology, OLS regression analyses were employed to measure the relative effect of principal influence on student achievement. The results of these analyses indicate that principal mindfulness made a statistically significant independent contribution to the variance in student achievement. For the qualitative interview data, a grounded theory approach was used to develop a conceptual framework for how mindful principals do their work. Three themes emerged endemically from these interviews, the results of which are presented in a concept map at the end of this article. (Contains 5 tables and 2 figures.)