[Who's That Knocking at My Door? explores] the hermetic environments of working-class post-immigrant American society…. Knocking's Italian-America [is a social structure] in which the isolation of imported nationalism and Roman Catholicism collides with dreary urban or industrial town living to produce characters somewhat dislocated in time and place. [The film doesn't seem] quite up to date…. A world where guys still wear white shirts and grey suits to a party … becomes a world stable enough so that plot premises like … Knocking's Italo-Catholic obsessions with virgin brides become acceptable because no alternative forms of behavior are even suggested. If the results are somewhat synthetic and theatrical, they also have an admirable austerity and containment lacking in the wilder, so-called swinging movies so currently prevalent.

Synthetic and theatrical, too, are much of the [picture's] acting and dialogue. Lines seem lifted off the typewritten script-page and thrust into the mouths of the actors in desperate attempts to sound realistic. But all of the false starts, digressions, sputterings and silences of real conversation, while continually aped, become, in the attempt, all the more conspicuously affected and artificial under the camera-eye's glare…. Scorsese may not approve of his characters, or even like them, and he may handle them awkwardly at times, but at least he respects their humanity, which puts him far closer to early De Sica, or, more recently, Olmi, than any of Hollywood's aborted attempts of the fifties … Who's That Knocking at My Door? [is] ultimately most reminiscent of the old, somewhat over-written, T.V. "Playhouse 90" genre. It is as if that very genre which spawned Sidney Lumet and John Frankenheimer and so many others who were later to develop far more complex styles in film were now being nostalgically called-upon by young film-makers working in a style which, with its small frame, formal black and white, and comparatively low depth of field, is oddly similar to the old television image.