Introduction: The increased emphasis on standards-based schoolaccountability since the passage of the no child left behind act of2001 is focusing critical attention on the professional developmentof school principals and their ability to meet the challenges ofimproving the student outcomes. Due to this subject, the currentstudy examined professional development needs of Shiraz highschools principals.Methods: The statistical population consisted of 343 principalsof Shiraz high schools, of whom 250 subjects were selected usingKrejcie and Morgan (1978) sample size determination table. Tocollect the data, a questionnaire developed by Salazar (2007) wasadministered. This questionnaire was designed for professionaldevelopment in the leadership skills/competencies and consisted of25 items in each leadership performance domain using five-pointLikert-type scales. The content validity of the questionnaire wasconfirmed and the Cronbach’s Alpha coefficient was (α=0.78). Toanalyze the data, descriptive statistics and Paired-Samples t-testwere used. Also, the data was analyzed through SPSS14 software.Results: The findings showed that principals’ “Importance” ratingswere always higher than their “Actual proficiency” ratings. Themean score of the difference between “Importance” and “Actualproficiency” pair on “Organizing resources” was 2.11, making itthe highest “need” area. The lowest need area was “Managingthe organization and operational procedures” at 0.81. Also, theresults showed that there was a statistically significant differencebetween the means of the “Importance” and the correspondingmeans on the “Actual proficiency” (Difference of means=1.48,t=49.38, p<0.001).Conclusion: Based on the obtained results, the most importantprofessional development needs of the principals includedorganizing resources, resolving complex problems, understandingstudent development and learning, developing the vision and themission, building team commitment, understanding measurements,evaluation and assessment strategies, facilitating the changeprocess, solving problems and making decisions. In other words,the principals had statistically significant professional developmentneeds in all areas of the educational leadership. Also, the resultssuggested that today’s school principals need to grow and learnthroughout their careers by ongoing professional development.Keywords: Professional; Development; Need assessment; Educational leadership