Collecting data and working with classified information in restricted military settings can present significant research challenges. Academic ideals of transparency and openness clash with the military's need for secrecy and closedness. This article engages with existing literature on security requirements and research ethics in discussing practical challenges researchers face in military research. Even though military security requirements and principles of research ethics are often perceived as opposites, they also share characteristics: both realms are context-driven, nonobjective, and require professional judgment to assess. Through a four-part analysis corresponding to different steps in a research process, the authors develop a practiceoriented guide for researchers accessing and working with classified information in discussing mundane examples of how "insiders" with "privileged access" navigate between ethical research principles and security issues. The article also incites a broader debate on research governance, (self-)imposed restraints and the conditions for critical inquiry in the military domain.