This chapter evaluates attempts to define documentary film. I begin by addressing general skeptical concerns that the distinction is impossible, since all documentary is in fact fictional. Putting aside these sophomoric worries, I present the debate between Currie, Carroll, and Plantinga. Although Carroll's theory that documentaries are films of presumptive assertion is in many ways superior to Currie's, it nevertheless appears to suffer from some serious problems. Most notably, one might worry that it cannot distinguish between documentaries and biopics.