When Bertie tries to enliven the summer vacation by starting a "gang," everyone has an excuse not to join--even her best friend, whose mom is put off by the word (which was suggested by Bertie's lively Granny). Still, Bertie gathers a one-time crowd--but not a following--by offering free pizza, meanwhile antagonizing the neighborhood boys by excluding them. They start a rival gang, and a glorious watertight ends in friendship all around after a big, muddy kid--whom no one recognizes--proves to be Granny herself, prepared to be captain of a "one-sex gang" (after all, "Boys are people . . .Girls are people"). With its good-humored, on-target satire, this brisk, easily read "Springboard Book" is one of the better entries in the series. The well-individualized characters in Johnson's lively drawings add to the appeal.