Purpose: The present study investigates the capability of high school teachers' shared leadership perception to predict the academic optimism and organizational citizenship levels. Research methods: The population of the current descriptive study, which was conducted via screening model, consists of 321 high school teachers working for Amasya Directorate of National Education in the Spring term of the academic year 2012-2013. Research data were collected via Shared Leadership Scale, Academic Optimism Scale and Organizational Citizenship Scale. Findings: Multiple regression analysis was used to explore whether shared leadership perception predicts academic optimism and organizational citizenship behaviour. It was revealed that the strongest predictor of academic optimism perception was the emotional support dimension of shared leadership, while that of organizational citizenship behaviour was the joint completion of tasks dimension of shared leadership. Moreover, significant positive correlations (p < 0.05) were discovered between teachers' shared leadership perception and overall perception of academic optimism and organizational citizenship behaviour.