By converting all-day primary schools of suburban and urban areas in Greece into schools that implement the Comprehensive Reformed Educational Programme (CREP), a set of innovations were implemented, significantly altering the Greek school. The purpose of this study was to investigate the effect of selected variables over concerns of teachers who work at such schools. Additionally, this research asked the teachers to identify the professional development support and interventions required to enable them to make better use of the Book-reading Advancement (Philanagnosia) Activities innovation. Teachers’ administrative and pedagogical guidance executives, based on the above, will design the necessary interventions to positively address teachers’ concerns and implement the specific innovation in the most effective manner. Overall, the study found that higher teacher concerns were task related, with a significant record of information and self-concerns, which may indicate that the introduction of the innovation was not properly designed to address teachers’ primary concerns.