Principals are increasingly held accountable for school achievement. This paper reports the results of a mixed methods sequential Quan --> Qual research study to explore how middle school principals created a culture of academic optimism (AO) that promoted high student achievement (SA). Based on the analysis of AO scores from 26 schools, mostly high achieving, with a range of SES levels, a maximal variation sample of 11 principals from high-achieving schools was interviewed to identify strategies used to create a culture of academic optimism that fostered high SA. Results confirmed the advantage of mixed methods designs to pinpoint and explain complex principal leadership approaches by identifying strategies used by principals that had a positive relationship on AO and student achievement.