Lumen gentium no. 16’s genuine optimism for the salvation of non-Christians is nonetheless a heavily qualified one. Among other things, it applies only to those “who are, without fault, ignorant [sine culpa, ignorantes] of the Gospel of Christ and his Church.” This article examines (1) Vatican II’s understanding of such “inculpable ignorance” and its relationship to the traditional concept “invincible ignorance” and (2)—more speculatively—the extent to which it might apply in modern, Western societies.