Proof-writing is a core practice of mathematicians and a crucial skill every future teacher and mathematics major needs to acquire. A proof-based geometry course provides a fruitful ground for developing proof-writing skills. Despite recent pedagogical and technological advances proof remains difficult to learn and to teach. We conducted a pilot study to explore potential advantages of an innovative digital proof tool FullProof, which was developed with an exclusive goal of advancing students’ proof-writing skills in Euclidean Geometry. We integrated the FullProof tool with three Geometry (for Teachers) courses at three universities: Georgia Southern University, South Dakota State University, and the University of New Hampshire. In this talk, we report on the findings pertaining to students’ interactions with FullProof, their perceptions of the usefulness of this digital tool to their proof-writing skills, and the lessons learned from the FullProof integration in a Geometry course from an instructor perspective.