Purpose: The purpose of this paper is to examine the role of teachers' optimism and trust in their individual citizenship behavior (ICB), and the extent to which teachers' optimism is related to teachers' ICB, and mediated by teachers' trust. ICB is a concept coined by Hoy et al. (2008). The concept refers to teachers' voluntary and discretionary behavior directed toward colleagues, students, and the students' parents, that exceeds the formal job expectations. The primary aim of ICB is to enhance students' academic success. Design/methodology/approach: In all, 370 teachers from public elementary schools in northern Israel completed questionnaires, assessing teachers' optimism, trust, and ICB; the category was examined both by direct and projective measures. Factor and reliability analyses; a bi-variate correlation Pearson test; a hierarchical regression analysis; and a structural equation modeling (SEM) analysis were conducted to analyze the data. Findings: The research hypotheses were partially supported: teachers' optimism, trust, and ICB were positively correlated; teachers' optimism and trust predicted ICB; trust in students and their parents mediated the association between optimism and ICB, whereas trust in teachers mediated the association between optimism and the projective measure of ICB. Originality/value: The study results confirm that optimism and trust in students and their parents, and in other teachers have a significant presence in teachers' ICB; emphasize the importance of a positive school environment; emphasize the importance of teachers' ICB toward students' and their parents; indicate the potential benefit of using direct and projective measures; and show support for the mediating model.