This study aimed at evaluating the impact of Queen Rania Teacher Academy science teachers professional development program’s activities on teachers’ instructional practices by identifying the successes, challenge and ways to sustain the exemplary reformed instructional practices in the science classroom. The idea is to analyze participating science teachers’ reflections on a three-year journey of continuous professional development. Qualitative data collected in the form of participants’ self-reflection and field notes from 18 male and female participating science teachers. Findings indicate that even with effective professional development, science teachers encounter diverse challenges to implement the reformed instructional practices in the classroom. Teachers need support, time and resources to succeed in implementing what they learned in their classrooms. Findings also revealed that professional development efforts need to reveal and address existing teachers’ beliefs in order to be successful. Implications for future science continuous professional development efforts are discussed.