As doctoral enrolments have soared in many countries around the world, considerable attention has been devoted to how an increasingly diverse candidature can succeed in thesis writing. Along with supervisory guidance during the student's research project, various publications have emerged to help students with thesis writing requirements. However, neither necessarily helps students become expert writers as supervisors tend to focus on content discussions, and self-help books attend to the more surface or mechanical features of writing. Along the way to a finished thesis, students can become mired in uncertainty about what they are discovering -- intellectually stuck -- and then lose confidence in their ability to express themselves within an academically accepted writing style. Indecision hampers student progress as they struggle with appropriate ways to reveal the insights they are gaining during research. Yet, generic, group-oriented, doctoral writing programmes can provide a powerful means for students to appreciate key features of the doctoral writing genre and overcome intellectual hurdles. This paper explores how an understanding of threshold concepts and the use of cultural, social and linguistic tools can mediate students' emerging knowledge of how to become proficient and successful thesis writers.