The purpose of this study was to investigate the characteristics of effective professional development and effective models of professional development as perceived by school teachers in the State of Qatar. This study is quantitative in nature and was conducted using a survey methodology. Means, standard deviations, t-test, and one-way analysis of variance (ANOVA) were utilized to analyze the collected data. Results of the study revealed that school teachers in Qatar perceived the proposed characteristics of effective professional development to be highly effective. Further, school teachers in Qatar perceived mentoring model (mentoring model (providing professional support from experienced teacher to new hiring teacher) as the most effective professional development model. However, an online training program was rated to be the least effective professional development model. Finally, results showed that there are no significant differences among school teachers in perceiving the proposed characteristics of effective professional development and in perceiving the most and the least effective professional development models that are attributed to their gender, years of experience in teaching, and school level.