Stephanie, Layla, Alice and Nancy -- the group that eventually runs Medusa -- are the key ''big girls'' of Fay Weldon's latest novel, ''Big Girls Don't Cry,'' and given that Medusa sounds suspiciously like the British publishing house called Virago, their real-life counterparts may all be out there somewhere. But it isn't necessary to decode this roman a clef in order to enjoy it. Part ensemble piece (following the fortunes and misfortunes of its characters from 1971 to the present) and part feminist primer, ''Big Girls Don't Cry'' cruises through the decades, aided by a chatty narrator with a well-honed sense of irony and a knack for telescoping history.

There are at least three different ways of approaching Fay Weldon's 22nd novel. Anyone who knows anything about Virago will approach it curiously, since it's a surprisingly direct roman-a-clef based on the real people who founded that publishing house. And anyone who cares about British feminism will approach the book eagerly, because it is full of sweeping statements about where seventies feminism came from, what it achieved, and where it failed. But the third way to approach the book is the only way that should concern us here. Weldon has presented this mixture of gossip and polemic not as a piece of journalism, but as a novel, and so it deserves to be read and criticised as fiction.