The Harvard-Radcliffe Opportunes' Head of the Charles Jam was not a concert for the feeble-minded or faint of heart. Four a capella groups and three droll, yet tire-some, emcees gave the packed Sanders Theater crowd three and a half hours of orgiastic a capella excess.

Harvard groupies and their courser cousins, non-Harvard groupies, lapped up the sights, sounds and smells until they were saturated. By the end of the evening, some were still begging for more. Others were dazed, dizzy and slightly nauseated.

After hours of fun, excitement and intermission, the crowd itched to hear the Opportunes in a way that only hard-core a capella fans can itch. But when the first three songs did not sound up to snuff, people braced themselves for a very long set, and some left.

The Opportunes' first song, R.E.M.'s "Shiny Happy People," is not suited for an a capella arrangement, and even Conal Murray's solid solo could not make the song provide any aesthetic pleasure. But, three songs later, when Alyssa O'Farrell started singing "In Your Eyes," the Opportunes began to deliver the complex, daring arrangements topped by superb solos that make the group great. O'Farrell saved the night, and everyone in the audience was proud of her.

Toby Blackwell followed with a brilliant lead in "Midnight Train to Georgia." This number showcased the group's impressive singing abilities as well as its complicated choreography, which added that extra je ne sais quoi to their performances.

Lauren Bumby's "Material Girl" went smoothly--enough said. Kenya Thompson sung with such power and style that "Moondance" sounded excellent. And Shawna Cornelius doled out some "Sweet Love" in her sultry number.

The Opportunes alto section consistently displayed remarkable depth and should continue to figure prominently in their performances. Perhaps instead of including R.E.M. in their repertoire, the Opportunes should add more pieces by altos such as Kirsty MacColl or Sinead O'Connor.

The show ended with a spunky medley of tunes from the Seventies, and encores included Opportune standards "Zombie Jamboree" and the "Let the Music Play" mix. The crowd never can get enough of "Zombie," performed with flair by the whole group and especially by Casey Gallagher.

The set's humor was top-notch as always. Most notably, the "Clarence Thomas' English Muffins" skit hit the spot. Reminiscent of past Opportunes skits, it ranked among such classics as the group's miracle cure for yeast infections and their commercial for spring water douche.

As for the other groups of the night, the Pennsylvania 6-5000 provided some laid back, harmonious entertainment, although these 11 men were not sensitive guys. The Tufts Jackson Jills, an all-female group, sang only bad pop songs, but they were much stronger than the Wellesley Widows, who showcased their lack of talent last week.

Finally, the Dartmouth Aires had a clean sound, sang an inspired "Jesse's Girl," but lost the audience with their random humor. After watching two members of the group have a metaphysical light-saber duel with kilbasa sausages, the crowd was left waiting for Godot to arrive.

Emcess Glenn Kessler, Richard Claflin and Chad Leith had an amusing, Hasty Pudding kind of dynamic on stage. Although bits such as "The Home Shopping Period Network," "Hamlet-Cop" and an extended, musical version of "Knock Knock/ Who's There?/ Boo/ Boo Who?/ Hey there--dry your eyes!" were hilarious, perhaps the skits ran a tad long for this mother of all jams.

Stay tuned for Daniel Sharfstein's probing and insightful review of the Radcliffe Pitches, appearing on next week's Arts Page.