Although fairly powerful when originally released, One Is a Lonely Number seems more than a bit dated when seen today. An example of 1970s-era "issue-oriented" filmmaking, One comes across as a trifle too manipulative and melodramatic, although there are times when the screenwriter offers some genuinely perceptive or insightful comments, and, in general, the dialogue has some snap and life to it. Mel Stuart's direction tries too hard, but when he lets himself relax, he creates some lovely, "real" moments. What makes One worthwhile, however, is Trish Van Devere's beautifully calibrated performance. Looking absolutely stunning, the actress throws herself into the part, wringing every last bit of truth from the screenplay. She projects a tremendous warmth and vulnerability that is balanced by an appealing determination. Van Devere also displays a palpable sensuality, and her seduction of and romance with Monte Markham are quietly erotic. Markham is not up to his co-star's level, but she does get very fine support from a cynical, sarcastic Janet Leigh, a sympathetic Melvyn Douglas, and a winning Jane Elliot. On the whole, One falls short of the goals it sets for itself, but it makes a game attempt -- and Van Devere is well worth the price of admission.