Libraries of all kinds are uniquely positioned to educate and advocate for the use of privacy-protection technologies (PPT) by our patrons and in our communities; this naturally extends our decades-long mission to protect our patrons’ privacy in both digital and physical library environments. In pursuit of building an understanding of the challenges to expanding such work, this research study assesses librarians’ existing technical knowledge of the internet’s function, and their current use and understanding of a series of popular PPT. This research study begins to close the gap in research by building our knowledge of practicing librarians’ underlying assumptions about the function of the internet and how these internal models are employed in their understanding and use of PPT. Research study participants were asked to draw and explain their perception of the functioning of the internet, to use several PPT, and to explain the protections afforded by each technology. The findings indicate that participants maintained inaccurate mental models of the internet and PPT, leading to difficulties in understanding function, and that they struggled with organizational and technical barriers to integrating such technologies into their daily lives.