The study has widespread and important contributions. It is important to address happiness, which is one of the main areas of study supported by the European Union and the United Nations, in the context of schools. It is valuable to examine the reflection of the existence of happy individuals in educational institutions, especially when the importance and impact of the existence of happy individuals everywhere is very great. Depending on the results, the European Union and the United Nations can create happy schools and individuals by conducting more concrete research on the subject in order to increase the level of welfare. One of the important widespread effects of the study is to determine the applicability of innovation in schools, which is among the main fields of study supported by the European Union and the United Nations. Thus, it can be seen how much innovation-oriented schools contribute to the development of a country. In the current study, the issues of happiness and innovation in schools in Turkiye are discussed.

Leadership is defined as the process of influencing others to understand and agree on what needs to be done effectively and facilitating individual and collective efforts to realize the shared vision of an organization or nation. Innovative leaders have common attributes such as knowledge, skills, values, abilities and leadership aspirations that play the most important role in the success of innovative leadership practices. The nature of followers and internal and external factors also play an important role in their success (Blanchard & Stoner, 2004). A school can be effective when all its resources can be mobilized. Therefore, the school principal is at the top of the decision-making and coordination process (Özdemir, 2014). Because the results of studies on the effectiveness of schools reveal that school administrators play a primary role in ensuring efficiency and effectiveness in schools (Balcı, 1993). In addition, school administrators, with their skills, equipment and experience, play an active role in creating a vision for the organization, planning the future of the school, and channeling the stakeholders in the school in a positive direction. School happiness is also defined as the emotional relief that results from the harmony between the expectations of students and the personal needs of students, teachers, school administrators and other employees depending on certain environmental factors (Engels, Aelterman, Petegem & Schepens, 2004). In this context, the purpose of the study is to examine the mediating role of principal-teacher relationship in the relationship between innovative school leadership and school happiness. Four hypotheses developed in line with the purpose of the study were tested:
1. Innovative school leadership positively affects school happiness.
2. Innovative school leadership positively affects principal-teacher relationship.
3. Principal-teacher relationship positively affects school happiness.
4. Principal-teacher relationship mediates the relationship between innovative school leadership and school happiness.

The study was conducted according to the relational survey model to determine the relationships between innovative school leadership, principal-teacher relationship and school happiness. The population of the study consists of 2800 teachers working in secondary and high schools in Hakkari province of Turkey (Ministry of National Education [MoNE], 2024). The lower limit for the sample size of the study is 339 according to 95% confidence interval. The sample of the study consists of 400 teachers working in middle and high schools in Hakkari province in the 2023-2024 academic year. In the study, “Innovative school leadership scale” developed by Akyürek and Karabay (2022) was used to determine innovative school leadership. “School happiness scale” developed by Sezer and Can (2019) was used to determine the level of school happiness. “Principal-teacher relationship scale” developed by Zee et al. (2023) and adapted into Turkish by Gümüş et al. (2018) was used to determine the principal-teacher relationship. The scales were found to be valid and reliable as a result of confirmatory factor analysis for validity analysis and item analysis using item-total correlation and cronbach alpha for reliability analysis. In addition, regression analysis based on the Bootstrap method was performed to determine the mediator as the data were normally distributed.

In Turkiye, the European Union and the United Nations, it has been concluded that happy individuals and schools contribute to school effectiveness with innovation. Especially the presence of innovative school leaders has a greater and positive impact on this process. One of the most important indicators of this is that the principal-teacher relationship has turned into a solid structure with the happiness of the teachers. Multicultural studies can be planned at the European Union and the United Nations to study these issues in depth. Because intercultural diversity can play a role in happiness and innovation. It was found that teachers' perceptions of innovative school leadership and school happiness were high, while their perceptions of principal-teacher relationship were at medium level. In addition, it was found that there were significant positive relationships between innovative school leadership and school happiness at high level, between innovative school leadership and principal-teacher relationship and between school happiness and principal-teacher relationship at medium level. With the existence of high happiness and innovation in schools, effective leadership and strong principal-teacher relationship can be mentioned. In addition, it was determined that the indirect effect of innovative school leadership on school happiness was significant, and thus, principal-teacher relationship mediated the relationship between innovative school leadership and school happiness.

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