Risk assessment and risk reduction have become increasingly central to criminal justice policy and practice in the last 25 years. Yet there remains a lack of consensus both on the theoretical and methodological foundations of risk and on its social and practical implications. Some proponents see risk assessment and reduction as solutions to the inefficiencies and injustices of contemporary mass incarceration. Some critics see actuarial risk as being partially responsible for mass incarceration, and warn that recent iterations will only reinscribe existing inequalities under a new guise of objectivity. Both perspectives contain elements of truth, but each falls short because neither adequately specifies the different dimensions of risk that condition its effects. Using two prominent frameworks as foils, this article excavates the contested terrain of risk assessment and exposes a set of distinctions that can inform the use-and prevent the abuse-of risk knowledge in criminal justice policy.