With the coming of summer, the guitar-playing Harvard hillbilly disappears into the foothills west of Worcester and leaves the community to its own musical resources. An unusually active undergraduate dramatic scene also fades, throwing the Summer School into a more professional, although not always accomplished, world of the theatre.

Throughout the summer session there is considerable dramatic and musical activity calculated to divert students from the more engaging quest for the humid, under-the-shade-tree liberal education.

A thirty-minute drive from Cambridge via Route 16 will take one to Wellesley College, residence of the Group 20 Players. Calling themselves "America's Oldest Classic Theatre," the Players appear on the Theatre-on-the-Green, a beautiful Greek theatre located near Lake Waban's equally beautiful pathways.

With their season running from June 24 to August 30, the Group 20 Players present a variagated series of plays, each running two weeks. Sheridan's The School for Scandal, the current production runs until July 5. From July 8 to July 19, the Players will stage Arthur's Miller's Death of a Salesman. For the remainder of the summer, The Merchant of Venice, Pygmalion, and Jean Giraudoux's Tiger at the Gates will appear.

There are no performances on Sunday nights, but every Monday night preceding an opening the Players stage a special public dress rehearsal.

Tufts Arena Theatre at Medford, a twenty-minute drive from the Square, offers a weekly show by a semi-professional company. The Reluctant Debutante will appear through July 5, and student tickets for all performances can be bought for a small fee.

Closer to the Square, however, is the Boston Summer Theatre, at New England Mutual Hall. Opening July 7 with Bert Lahr in Visit to a Small Planet, the Summer Theatre will also present James Mason in Mid-Summer (July 14-19); Basil Rathbone and Geraldine Page in Separate Tables (July 21-26); Tonight at 8:30, with Faye Emerson (July 28-Aug. 2); Hal March in A Hole in the Head (Aug. 4-9); Dulcy, with Dody Goodman (Aug. 11-16); and Melvyn Douglas in Strange Partners, a new play by Florence Lowe and Caroline Francke (Aug. 18-23).

The American Shakespeare Festival, at Stratford, Conn., will present Hamlet, A Midsummer Night's Dream, and The Winter's Tale throughout the summer. The third play, however, will not be performed until July 20, and will appear thereafter at scattered dates, with its last performance on August 2.

Located between Bridgeport and New Haven, Stratford can be easily reached by train or by automobile. By using the Massachusetts Turnpike, one can drive there in about three hours.

If one plans to spend a week-end in Stratford, it is advisable to make arrangements in advance. While (shudder) New Haven and Bridgeport are not exactly resort towns, there are numerous hotels and motels in both places. The Festival stands ready to make reservations in advance.

Cape Cod, always a pleasure playground in the summer, has many outstanding companies, including the Provincetown Players, appearing at the Playhouse on the Wharf. The Players open on July 3 with A Moon for the Misbegotten, and continue through the season with The Climate of Eden (July 14-19), The Family Reunion, Separate Tables (July 28-Aug. 2), The Emperor Jones (Aug. 4-9), The Summer's Treason (Aug. 11-16), and The Millionairess (Aug. 18-23).

On the musical side, there is the always popular and rewarding Berkshire Music Festival at Lenox. The Boston Symphony Orchestra, conducted by Charles Munch and Pierre Monteux, will perform with other musical groups, including the Berkshire Music Center Orchestra and the Tanglewood Choir.

On Sunday, July 6, at 2:30 p.m., the Harvard Glee Club and Radcliffe Choral Society will perform Bach's B Minor Mass. G. Wallace Woodworth, who retired in June after twenty-five years as conductor of the HGC, will return to lead the Boston Symphony and HGS-RCS.

To reach Tanglewood by automobile, take the Mass. Turnpike to Exit 2. Tickets to the lawn are on sale at all gates before each scheduled concert.

Arthur Fiedler and the Boston Pops will let go with all the standard summer-time goodies nightly on the Esplanade. To reach these free open-air concerts, take the subway from Harvard Square to the Charles Station exit.

For even more low-brow, down-and-out entertainment, the seasonal over-flowing of musical comedies should not be overlooked. From the Cape working their way westward, professionals, hacks, and just plain hams tiptoe through the tulips, sweetly and lightly.

The North Shore Music Theatre at Beverly (Exit 9 on Route 128) will present The Most Happy Fella through July 5, and continue its season with Roberta (July 7-12), Paint Your Wagon (July 14-19), Girl Crazy (July 21-26), Can Can (July 28-Aug. 9), Kiss Me, Kate (Aug. 11-16), and Fanny (Aug. 18-23).

Cohasset is the home of the South Shore Music Circus, which will offer a compendium of famous musicals. Damn Yankees runs until July 12, and will be followed by Guys and Dolls (July 14-19), Happy Hunting (July 21-26), Fanny (July 28-Aug.9), Where's Charley? (Aug. 11-16), and The Most Happy Fella (Aug. 18-30).

And finally there are the concerts at the Gardner Museum in Boston, held every Tuesday, Thursday, and Saturday at 2:45 and every Sunday at 3 p.m. The admission is free.