Abstract: Digital literacy plays an important role in adapting education systems for the 21st century. Previous research indicates that teachers' main difficulties in assimilating technology in teaching stem from environmental or personal blocks and negative attitudes concerning computer-assisted teaching. Avidov-Ungar and Amir (2015) noted a gap between positive attitudes concerning computer-assisted teaching and actual use of computers in teaching writing, which is relatively low due to a "discipline block". This study investigated an intervention program for professional development focusing on assimilation of disciplinary digital literacy to advance the discipline of writing instruction. The intervention program aimed to reduce the "discipline block" among high-school teachers working to advance writing. 92 teachers teaching writing participated in the study. Data collected from semi-structured interviews and self-report questionnaires. Findings indicate that most teachers felt the program was effective. Main characteristics perceived as helping teachers to assimilate technological tools in teaching included: profound understanding of specific digital tools for their discipline, receiving explicit instructions for application of these tools and actual use of the tools in the classroom. The teachers felt the intervention program increased their sense of self-efficacy and pleasure, enhancing motivation. The findings have implications for teachers' professional development.