This article reports on a series of carefully curated professional development (PD) activities with the secondary purpose of building and maintaining a positive school culture. The study took place in a school of foreign languages (SFL) at a state university in Turkey. Twenty-five Turkish and international teachers participated. The researchers collected data over a period of six months using a mixed-methods approach: a two-stage survey and semi-structured interviews. Three main themes emerged from the analysis; (1) the basic tenets of Continuing Professional Development (CPD), (2) factors that foster positive school culture, and (3) factors that undermine positive school culture. The results suggest that carefully curated PD has a positive impact on school culture; a combination of formal and informal PD offerings formed desired habits of mind among instructors. Moreover, instructors indicated a preference for peer-led PD. Thus, we suggest that other SFLs in Turkey likewise harness the untapped potential of the CPD Unit.