This is a movie about disguise, denial, alienation and the terrible toll taken on the people who make a stand that their fearful or resentful contemporaries see as odd, eccentric or foolhardy – but will later sheepishly admit were entirely right.

Peter Bradshaw

The Guardian

Director Sidney Lumet (working from a screenplay by Waldo Salt and Norman Wexler) chooses not to press the superheroic aspect of his protagonist. Serpico is more street-level, tracing a decade of NYPD change--and refusal to change--through an episodic, often elliptical structure.

Noel Murray

The A.V. Club