We consider all-pay auctions with private and affiliated binary values. The organizer commits ex ante to fully disclosing or concealing bidders’ valuations. We examine the effects of full disclosure on bidders’ welfare and the organizer’s revenue (i.e., expected aggregate bid). We find that full disclosure, as opposed to full concealment, always yields a higher welfare for bidders. On the other hand, full concealment yields a higher revenue if the affiliation in bidders’ valuations is low or if there are only two bidders. Conversely, if the affiliation is high and there are sufficiently many bidders, full disclosure tends to increase revenue.