This chapter investigates ‘forbidden’ knowledge, examining the structures and processes that impede the production of knowledge, and how such knowledge can threaten powerful interests mediated through institutions and sociopolitical and religious cultures. This can entail both formal and informal processes including self-censorship, peer review, internal university restrictions, and external sociopolitical restrictions. The chapter considers the construct of ‘forbidden’ knowledge, recognising it as more than gaps in knowledge, and also in terms of structural and sociopolitical processes, consolidating this knowledge as too dangerous or ‘taboo’ to produce. Drawing on empirical accounts of the daily lived experiences of academics operating within this terrain, four areas of forbidden knowledge – ‘bioethics, psychology, and genetics’; ‘Palestine’; ‘gender and sexuality; and ‘race, religion, security, and extremism’ are explored. In addition, questions of power, agency, positionality, and sociopolitical and historical contexts are critically elucidated.