This study was focused on high school principals’ happiness and effective instructional management and also the relation between them. The methodology of this research was descriptive and correlative. The two questionnaires employed here were “The Oxford Happiness Questionnaire” and “Principal Effectiveness Measures” with five component measures of effective principal. SPSS 15 was used to produce Mean, Standard Deviations, Pearson Product Moment Correlation (r), t-test, and ANOVA. The results of the study showed that the high school principals described their happiness in high level and also in overall marked high scores on effective instructional management and components of effective management: Organizational Commitment (OC), Sense of Community (SoC), Productivity and Effort (PaE), Job Satisfaction (JS), and Employee Morale (EM). There was relatively high positive correlation between principals’ happiness and effective instructional management and components of effective management. The analysis of data showed that there were no significant differences on principals’ happiness and effective instructional management in terms of their background, such as age, sex, marital status, teaching and management experiences.