In my practice as a psychotherapist, I’ve seen an increase of depression in young men who feel emasculated in a society that is hostile to masculinity. New guidelines from the American Psychological Association defining “traditional masculinity” as a pathological state are likely only to make matters worse.

True, over the past half-century ideas about femininity and masculinity have evolved, sometimes for the better. But the APA guidelines demonize masculinity rather than embracing its positive aspects. In a press release,...