New York A generation after its 1950 Broadway success, ''The Country Girl'' proves its durability in the production at the smart new Chelsea Playhouse on West 23rd Street. Clifford Odets's emotionally charged drama about a crucial turning point in the lives of an alcoholic actor and his steadfast wife retains its power to hold and to move an audience. The plotting may seem at times forced and contrived in these days of retreat from slice-of-life drama. But the author's realistic depiction of the travails of playmaking - including the totally unglamorous milieu in which theatrical glamour is created - give ''The Country Girl'' its drab authenticity. More important, Odets created in his central situation a trio of characters whose capacity to survive in stage fiction resides in their believability as human beings. ''The Country Girl'' centers on the consequences of an attempt by brash young director Bernie Dodd (Jeffrey DeMunn) to rehabilitate the career of Frank Elgin (Hal Holbrook), a once-talented actor who has drunk his career away. The obtusely self-confident Bernie fails to recognize that Frank's wife, Georgie (Christine Lahti), is the only solid fixture in Frank's demoralized life. Mr. Holbrook brings out all of Elgin's latent power. At the same time this excellent actor gives an unsparing portrait of a man whose self-pity and shameless duplicity are part of his self-destructiveness - a performance excellently matched by his co-stars. In a relationship that begins with hostilities and ends in something more than mutual respect, Miss Lahti's enduring Georgie and Mr. DeMunn's aggressive but talented Bernie undertake the task of reclaiming Elgin. The flavor of backstage life is convincingly sustained by a cast that includes Victor Raider-Wexler as an icy producer and Gus Kaikkonen as the author of the script, whose perilous progress parallels the events of the drama. Richard Thomsen has directed ''The Country Girl'' with an appreciation for its calculated theatricalism. A partial proscenium arch looms over Jack Chandler's flexible settings. The revival was costumed by Julie Schwolow and lighted by Phil Monat. She Stoops to Conquer Comedy by Oliver Goldsmith. Directed by Daniel Gerroll. Starring Kaye Ballard , Tovah Feldshuh, E. G. Marshall. The Roundabout Theatre Company is celebrating the 20th anniversary of its founding with a good-natured revival of a sturdy 18th-century comedy classic. Oliver Goldsmith's ''She Stoops to Conquer'' was originally entitled, ''The Mistakes of a Night,'' which became its subtitle. The series of mistakes and mistaken identities generates the amusing mix-ups that take place in the English countryside a little over 50 miles west of London in September of 1744. The mistakes begin when young Marlow (Norman Show) is duped into believing that the home of his designated father-in-law, Squire Hardcastle (E. G. Marshall), is a wayside inn. The cause of the young man's unaccountable behavior is known only to Hardcastle's stepson, the rascally Tony Lumpkin (Nathan Lane), who perpetrates the hoax but who, in the end, proves to be more of a friendly conspirator than a lumpish bumpkin. The animated performance, directed by Daniel Gerroll, had not yet quite achieved an easy ensemble at the preview I attended. But there was no mistaking its comic intent. The attractive cast stars Mr. Marshall as the nonplused and outraged Hardcastle, Tovah Feldshuh as an entrancing Kate, and Kaye Ballard as the affectedly voluble Mrs. Hardcastle. Mr. Lane sees Tony as something slightly more than merely one of the brattiest brats in English comic stage literature. Along with his pranks and werewolf cry, there is a certain style and wit to his mischiefmaking. John Bedford-Lloyd and Cynthia Dozier make an attractive twosome as the secondary lovers of the comedy. Set designer Robert Thayer has made a good effort to adapt the Triplex's awkwardly wide stage to the needs of the changing scene. But surely the Roundabout company could have afforded more than a single chair to furnish the Hardcastles' drawing room. Eloise Lunde created the picturesque period costumes and Allen Lee Hughes lighted the production. (The Triplex is the company's temporary home on the campus of Manhattan Community College/City University of New York, on Chambers Street, in the city's deep south. ''She Stoops to Conquer'' runs through Nov. 11.)
Play by Clifford Odets. Directed by Richard Thomsen. Starring Hal Holbrook, Jeffrey DeMunn, Christine Lahti.