Like Fritz Lang, Forman was an influential filmmaker in his homeland who went on to achieve comparable influence in Hollywood. Forman's Czechoslovakian films, including "Loves of a Blonde" (1965) and "The Fireman's Ball" (1967), marked a distinct thematic and stylistic break with the prior generation of filmmaking in that country and played a major role in shaping the Czech New Wave of the 1960s. These films were characterized by an ironic humor and detailed observation of character for which Forman has become well known.

A persistent theme in Forman's work is generational conflict, particularly as it is played out within a family or family-like context. Some critics have suggested that Forman's preoccupation with parent-child relationships may stem from the loss of his own parents in Nazi concentration camps. In Forman's first two features, "Black Peter" (1963) and "Loves of a Blonde", he deals with the theme in a gentle and humanistic manner, using it for subtle criticism of the socio-political climate in Czechoslovakia of the mid-60s. The political content of Forman's Czech films is rarely overt, but rather suggested through the harshly authentic depiction of a bleak environment and inflexible social order. To achieve this authenticity, Forman has routinely used non-professional actors who were often instructed to improvise their dialogue to achieve a sense of spontaneity. The political implications of Forman's realism have been complemented by his narratives, which, as in "Loves of a Blonde", often tell the story of young people struggling to find happiness and meaning within an established social order that has not provided for their personal and emotional fulfillment. In all his Czechoslovakian films, the political critique is gently ironic and the humanism abundant.

Forman's first two American films bear strong thematic and stylistic resemblance to his Czechoslovakian work. "Taking Off" (1971), a critical if not commercial success, developed the generation gap theme: a set of parents go in search of their runaway daughter in NYC. "One Flew Over the Cuckoo's Nest" (1975), explored the struggle of the individual against the establishment. This film solidified his stature in the US, became a box-office smash and was the second film in history to sweep the top five Academy Awards, earning Best Picture, Director, Actor (Jack Nicholson), Actress (Louise Fletcher) and Screenplay (Bo Goldman and Lawrence Hauben).

Forman continued to develop these themes in his subsequent work. Switching gears, he explored the musical genre in "Hair" (1979), adapting the quintessential anti-establishment stage show. Forman had originally been drawn to the material in the late 60s, but the rights were then unavailable. By the time the film was made, it had become a period piece and its loose, revue-like structure posed problems. Working with screenwriter Michael Weller, Forman reinterpreted the material, fashioning yet another tale of young people seeking something more than the conventions provided by society. The tribal aspects of the hippie lifestyle provided a familial context against which the main action played out. Forman staged several brilliant set pieces, particularly the "be-in" in Central Park and Cheryl Barnes' heartbreaking solo "Easy To Be Hard". Abetted by the exquisite camerawork of Miroslav Ondricek and Twyla Tharp's energetic choreography, "Hair" remains one of the best screen adaptations of a stage musical. Unfortunately, despite strong reviews, the film was not a box-office success. Too much time had passed and other films had significantly dealt with the 60s and the Vietnam experience.

Forman followed with the period drama "Ragtime" (1981) that was noted more for marking the screen return of veteran actor James Cagney. Again collaborating with screenwriter Weller, he undertook the daunting task of translating E L Doctorow's sprawling, multi-character novel. Forman chose to concentrate on a few of the book's storylines, notably that of Coalhouse Walker Jr, a proud black musician who faces a choice of humiliation or defiance. The resulting film, while visually stunning and featuring several fine performances (including Cagney's police commissioner and the late Howard E Rollins Jr's Coalhouse), was a financial failure. Forman's original cut ran close to three hours; it was edited at the urging of the studio and producer Dino Di Laurentiis and the narrative structure somehow suffered.

For his next project, the director undertook adapting Peter Shaffer's award-winning play "Amadeus" (1984). The film played upon one of Forman's favorite themes, generational conflict (e.g., an older composer, Salieri, jealous of the youthful upstart Mozart; Mozart and his prickly realtionship with his father). Filming provided the helmer with an emotionally fraught set of circumstances. In his memoir, "Turnaround" (Random House, 1993), Forman details obtaining a visa to visit his homeland and the resulting sentiments of working in Prague. "Amadeus" was another visually stunning, well-acted piece and the American public responded to it. The film earned eight Oscars, including Best Picture, Actor (F Murray Abraham as the embittered Salieri), Screenplay (Shaffer) and a second Best Director Award for Forman.

Forman moved to academia in the late 1970s, teaching at Columbia University and eventually becoming co-director of its film program. After a five year break (during which time he had acted in two films, Mike Nichols' "Heartburn", 1986 and Henry Jaglom's "New Year's Day", 1989), he returned to features to helm an adaptation of Choderlos de Laclos' epistolary novel "Les Liaisons Dangereuses". Forman had first become interested in the material while an undergraduate studying with Milan Kundera. Despite a competing project, "Dangerous Liaisons" (1988), Stephen Frears' adaptation of Christopher Hampton's play, the director pushed on. Casting more youthful actors (Annette Bening, Colin Firth, Meg Tilly), Forman helmed a less pungent version of the story. Audiences had embraced Frears' acerbic take and high powered cast (Glenn Close, John Malkovich, Michelle Pfeiffer) and all but ignored Forman's. Its disappointing box office was tempered for the director by the democratic revolution in his homeland that saw his old friend, Vaclav Havel become president.

Much of Forman's attention in the early 90s was occupied with his duties at Columbia University and with developing his first original screenplay, the unproduced "Hell Camp", which focused on two Americans attending a school for managers in Japan. Forman was also at one time attached to direct "Disclosure" (1994), but he left the project in 1993 and was eventually replaced by Barry Levinson. He finally returned to the screen with the biopic, "The People vs. Larry Flynt" (1996). Again, Forman's themes of political conflict are baldly played out in this somewhat sanitized depiction of pornographer Flynt's First Amendment lawsuit. Produced by Oliver Stone, the film, which utilizes humor to make social commentary, won critical attention and audiences in big cities, although it failed to attract viewers in the South and Midwest.