Dr. Joseph Cardin is an important character in The Children’s Hour because of his romantic relationship with Karen Wright and the effort he expends in trying to quash the unfounded rumors about her alleged sexual relationship with Martha Dobie. Initially, the fact that Karen has a male fiancé seems to function as proof that she is straight. Joe dismisses the possibility that there is any foundation for Mary Tilford’s accusation that Karen and Martha are involved in a relationship. Joe becomes an important third member of their team as they unite to combat the libelous rumors that Mary and her grandmother are spreading.

Along with his support for the two friends, Joe also provides a source of conflict between the women. Martha is portrayed as insecure and dependent on her friend, to the point of worrying about their friendship ending after Karen’s marriage. The time Joe spends advocating on their behalf probably brings him into greater contact with Martha than he would have had otherwise. His interactions with the two of them make him more aware of their closeness, to the point he begins to wonder if there might be a sexual component. Regardless of the actual facts, the combined pressure of community opinion and the doubts he experiences eat into his relationship with Karen. In the end, their engagement cannot withstand the ordeal they have been through, and he agrees with Karen that they should split up.