His movies from this period include Gentleman's Fate (1931) with John Gilbert (filmed at M-G-M studios), Tonight or Never (1931), with Gloria Swanson, High Pressure, a proto-screwball comedy with William Powell and Evelyn Brent, and The Heart of New York (1932) with Joe Smith.

"[58][59] The social perspective of films favored at Warner Brothers was distinct from those of its chief rivals: Metro-Goldwyn-Mayer (M-G-M), uncontested for its "technical virtuosity" aimed to serve "middle-class tastes" and Paramount studios identified for its "sophisticated dialogue and baroque settings" that catered to European sensibilities.

What their films lacked in gloss in comparison to M-G-M or the sophistication of Paramount was more than adequately compensated for by their presentation of everyday material...the working classes could identify with people, the situations and surroundings...[62]LeRoy's output in the early Thirties was prodigious.

"[64][65] LeRoy's social realism mocked corrupt politicians, bankers and the idle rich, while celebrating the Depression Era experiences of "hard-working chorus girls...taxi-drivers and bell-hops struggling to make ends meet in the brawl of New York...gloss and polish were considered useless affectation.

—Iconic last words of fictional mob boss Enrico Bandello in "Little Caesar"[68][69] LeRoy first departed from his comedy-romance themed films with his drama Numbered Men (1930), a character study of convicts shot on location at San Quentin prison.

[70][71] The gangster film as a genre was not achieved until LeRoy's 1930 Little Caesar, starring Edward G. Robinson, the first time that "any real attempt was made by Hollywood to describe the brutal reality of the criminal world.

[73] LeRoy's adroit cinematic handling of Robinson's Rico incrementally shifts initial audience response from revulsion at the character's homicidal acts to a "grudging admiration" that provides for a measure of sympathy when the gangster meets his sordid death in a back alley.

"—Andrew Sarris (The American Cinema, 1968)[91] LeRoy's control of the comedic elements and his direction of a cast endowed with "hard-boiled" heroines Ruby Keeler, Joan Blondell, Aline MacMahon and Ginger Rogers, would provide stand-alone entertainment even if unencumbered by Berkeley's choreographed numbers.

LeRoy effectively employed cinematic techniques of montage, structural parallels in settings, chiaroscuro lighting and musical leitmotifs to develop atmosphere and convey O'Brien's struggle, ending in his vindication.

[104][105] The sheer scale of the project remains impressive, and LeRoy's ability to handle a film with high production values that possessed a "Metro-like glossiness" elevated him to becoming a protective executive producer at Metro-Goldwyn-Mayer.

[106][107] The "lively performances" from a large cast, which included Fredric March, Olivia de Havilland, Claude Rains, Anita Louise and Gale Sondergaard, as well as LeRoy's "technical excellence," led to five Academy Award nominations.

[116] According to critic Kingsley Canham, LeRoy's handling of tracking and low-angle shots, overhead composition, close-ups and dissolves possess a "visual power" that "retains its impact for modern audiences.

A look, a gesture, a touch can convey much more meaning than spoken sentences [and] that's the way we played the scene...[144][145]LeRoy directed Robert Taylor, Norma Shearer and Conrad Veidt in the 1940 Escape, the first of a number of anti-Nazi features suppressed by Hitler and which ultimately led to the banning of all M-G-M pictures in Germany.

[155] Random Harvest (1942): LeRoy and producer Sydney Franklin paired Garson with fellow Briton Ronald Colman in a romance that dramatizes clinical amnesia suffered by a WWI combat veteran.

[157] LeRoy's leisurely narrative pace, the lavishness of the settings, the fulsome musical score and the balanced editing demonstrate his embrace of M-G-M production values and distinguishing the stylish Random Harvest from his work at Warner Brothers.

Lives of the great and famous proved, as always, tempting material: authors, saints, politicians, scientists, inventors and tycoons received solid if none too accurate tributes…[161]LeRoy and producer Sydney Franklin made a genuine effort to make the "highbrow" subject of the film – the heroic discovery of radium isotopes – engaging to the public, resorting to romanticizing and simplifying the topic.

LeRoy employs flashbacks in an effort to present the personal lives of the airmen and their spouses, including an emotionally wrought scene in which the wounded Lieutenant Ted W. Lawson (played by Van Johnson) has his leg amputated.

[171][172] Conceived as a morale-builder for the homefront, Thirty Seconds Over Tokyo, with a script written by Dalton Trumbo "lacks the scope and organization" and compares unfavorably to director John Cromwell's 1943 Since You Went Away according to critic Kingsley Canham.

These purgings were considered, in some financial circles and the anti-Communist establishment, a necessary corrective to labor militancy in the industry: "To some observers, [the blacklist] represented a long overdue housecleaning process; to others it meant the beginning of an era of fear, betrayal and witch-hunting hysteria.

Filmed at the Cinecittà Studios in Rome, the production required the mobilization of tens of thousands of extras, more than nine months of shooting and an immense financial risk for M-G-M.[207][208] The huge investment in time and money paid off: Second only to Gone with the Wind (1939) in gross earnings, Quo Vadis garnered eight Academy Award nominations in 1952.

[210] In the aftermath of his successful epic Quo Vadis, LeRoy turned away from spectacles to lighter productions:[211][212] Lovely to Look At (1952): A re-make of the 1935 Astaire-Rogers musical scored by Jerome Kern, Roberta, directed by William A. Seiter.

Vincente Minnelli organized the extravagant fashion show finale, with costumes by Adrian[213][214] Million Dollar Mermaid (1952): An aquatic-themed biopic loosely based on the life of Australian swimmer Annette Kellerman, portrayed by Esther Williams and aided by LeRoy's "competent direction."

The Bad Seed (1956): The film is based on a story by William March about a disturbed eleven-year-old girl whose murderous behavior is credited to her genetic heritage: she is the granddaughter of a notorious serial killer.

[233] Toward the Unknown (1956): A sympathetic dramatization of a former Korean War POW, played by William Holden, who struggles to recover from post-traumatic stress disorder (PTSD) and return to service as a test pilot in the U.S. Air Force.

[235][236] Home Before Dark (1958): Based on a story and screenplay by Robert and Eileen Bassing, LeRoy examines the struggle of a former mental patient (Jean Simmons) to normalize her relationships with her husband (Dan O'Herlihy), who she suspects of having an affair with her half-sister (Rhonda Fleming).

[242][243] Wake Me When It's Over (1960), 20th Century Fox: A comedy-of-errors, starring Ernie Kovacs and Dick Shawn, involving the appropriation of post-WWII army surplus to build a resort on a remote Japanese island occupied by US troops.

[244][245] The Devil at 4 O'Clock (1961), Columbia Pictures: A priest (Spencer Tracy) and a convict (Frank Sinatra) join forces to rescue children from a leper colony when a volcano eruption threatens their Polynesian island.

Stage actors Gertrude Berg and Cedric Hardwicke were replaced by producer Jack L. Warner with film stars Rosalind Russell and Alec Guinness as the romantic leads, and the story set in Japan.

Rejecting Warners offer of Douglas Fairbanks, Jr., LeRoy spotted Gable in a touring production of The Last Mile at the Majestic Theatre in Los Angeles in the role of Killer Mears, and arranged a screen test with the stage actor.

[271][272] Audrey Hepburn: During casting for M-G-M's 1950 biblical epic Quo Vadis LeRoy sought an unknown actress for the role of Lygia, the young Christian loved by centurion Marcus Vinicius, played by (Robert Taylor).