Truth commissions have become so fashionable in times of transition that one can readily recognize what might be called a ‘truth cascade.’ The commissions, and the reports they produce, are reputed to promote many of the goals at the heart of the transitional justice project: helping victims to heal, promoting accountability, drawing a bright line between the past and the present, promoting reconciliation and so forth. And yet, a closer look at the truth-seeking enterprise suggests that it may not be able to deliver on these promises. This article explores both the intrinsic and instrumental reasons why truth commissions may not be effective in promoting the goals attributed to them. The article does not argue that transitional governments should not pursue the truth, but it does urge governments to use caution and careful planning when they do so.