We examined the extent to which a trainee's gender interacts with the gender of the trainer, as well as the gender composition of the classroom, to influence the trainee's knowledge acquisition. Hypotheses based on asymmetrical relational demography arguments were tested with a multilevel model on data collected from 1,515 predominantly Hispanic adult trainees in 115 classrooms taught by a total of 22 different trainers. Results supported an asymmetrical relational demography effect for the relationship between trainee-trainer gender dissimilarity and knowledge acquisition, such that trainer-trainee dissimilarity was related to knowledge acquisition for female trainees, but not for male trainees. No effects on trainee knowledge acquisition were observed for the trainee gender and classroom gender composition interaction. Exploratory analyses suggested that the racial diversity of the classroom was related to the knowledge acquisition of female trainees, but not male trainees.