Recently, studies have stressed the need to enhance teachers' professional development, particularly professional competence. Nevertheless, less research is conducted to fill the gap between theoretical knowledge and actual classroom practices. Therefore, this study aimed at investigating the effect of using the sheltered instruction observation protocol (SIOP) model on EFL student teachers' professional competence. To fulfill this purpose, 48 EFL student teachers enrolled in the third year, English Section at the Faculty of Specific Education, Zagazig University were chosen as the study sample. They were divided into two equal groups: an experimental group (n= 24) and a control one (n= 24). To obtain data collection, a pre-post professional competence observation checklist was designed to assess students' level before and after treatment. Findings revealed that the experimental group surpassed the control one in the overall professional competence and its dimensions, ie knowledge and understanding, skills, and dispositions. Data analysis also revealed significant improvement in the first two dimensions.