Four experiments investigated classroom learning by deaf college students receiving lectures from instructors signing for themselves or using interpreters. Deaf students' prior content knowledge, scores on postlecture assessments of content learning, and gain scores were compared to those of hearing classmates. Consistent with prior research, deaf students, on average, came into and left the classroom with less content knowledge than hearing peers, and use of simultaneous communication (sign and speech together) and American Sign Language (ASL) apparently were equally effective for deaf students' learning of the material. Students' self-rated sign language skills were not significantly related to performance. Two new findings were of particular importance. First, direct and mediated instruction (via interpreting) were equally effective for deaf college students under the several conditions employed here. Second, despite coming into the classroom with the disadvantage of having less content knowledge, deaf students' gain scores generally did not differ from those of their hearing peers. Possible explanations for these findings are considered.