What caught my attention in the acknowledgments to Jean Zimmerman’s “The Women of the House” (Harcourt, 400 pages, $26) — which her publisher calls a “bold, vivid narrative” full of “sensual, gritty detail” that “challenges our assumptions about colonial women”— is her tribute to Josepha Mulaire, who “continually reassured me that it is the imagining that makes history real.” She thanks several others for “beefing up my confidence.”

Why the need for continual reassurance about what makes history real? Checking the notes, I see why: The facts about the four “women of the house” could probably be put down in about 1,000 words. Ms. Zimmerman, then, is in the same pickle as Shakespeare’s biographers: working without the benefit of her subjects’ letters, diaries, or journals, although key legal documents, ship records, and the writings of others help pinpoint certain events in the biographical subjects’ lives.

Consequently, Ms. Zimmerman, like generations of other biographers, resorts to her “imagining,” which in practice means situating her subjects in the context of their periods (1660–1775). On this score, the biographer is superb. The way the world of colonial America looked, smelled, and sounded is beautifully evoked and based on extensive and shrewd historical research.

Here is what Ms. Zimmerman’s publisher means by “bold”:

At the bow of the yacht, her fingers gripping the rail, a young woman stood face into a wind that had buffeted the ship for days with a cocktail of freshmown hay, pine sap, and even the sweetness of wildflowers. Behind her, the pilot leaned all his weight on the tiller to thread the vessel thorough the Narrows, the Hoofden, where even the most seasoned skippers had been known to founder their ships on knife-sharp shoals. The little ship skimmed across the bright open lake called the Upper Bay, and then made its way through one final channel. Finally, a harbor town materialized all at once out of the haze, still a musket shot away but close enough to make out the fort, towering above everything, and the sparse forest of masts in the roadstead before it, colored pennants drooping in the still summer air. As the ship pushed closer, the dense heat of the land descended upon the deck like a wet sponge.

Thus begins a description of Margaret Hardenbroeck aboard a 17-thcentury ship entering New Amsterdam Harbor. In creating this scene, the biographer had access to maps and books galore. But where, pray, comes the novel-like picture of Margaret at the bow of the ship gripping the rail? The notes section is no help here. How could it be? Short of Margaret’s describing how she behaved on entering New Amsterdam Harbor, whether she gripped or clutched the railing (I propose clutched because I suspect she was rather ill after the long sea voyage) no one can know.

As a metaphorical opening, however, the passage works, since it conveys how strong and aggressive Margaret was. She does not fit the standard picture of a colonial woman because she was her own person. She already had a job as a debt collector for one of her relatives, and she would marry Frederick Philipse, a well-to-do man several decades her senior, and amass a fortune of her own by trading and real estate deals that would make her the wealthiest woman in the colonies. Even in her lifetime, though, the unusually tolerant Dutch rule that allowed single women to voyage across the sea and run their own concerns gave way after the British takeover of New Amstersdam, during which Margaret found herself employing her own husband as a “financial beard” in order to stay in business.

Margaret’s story dominates more than half the book, and, after she dies, the world of the entrepreneurial woman and the interest in Ms. Zimmerman’s narrative attenuates. The biographers’s other female subjects — all related to Margaret — have much more constricted personalities hemmed in by a male-dominated culture: Catherine Van Cortlandt Philipse (Margaret’s second husband’s wife) is a homebody whose claim to fame is her successful effort to build a grand church; Joanna Brockholst Philipse, the wife of Margaret’s grandson, Frederick Philipse II, is notable only for abetting her husband’s political career; and Johanna’s daughter, Mary Philipse Morris, in spite of Ms. Zimmerman’s calling her the “It girl” of the mid-1700s, was hardly more than a beautiful object who rejected the attentions of George Washington and married a man who is described as having a “Clara Bow mouth”! Poor pockmarked George (he had contracted small pox in Barbados) was not so attractive as Roger Morris with his “big moist eyes.”

Ms. Zimmerman’s sumptuous descriptions of social history and environment never flag, but after reveling in the bracing world of Margaret’s transactions (she often went to court to get her way, even with her second husband), these other women pale. Each succeeding generation seems to devolve into a narrower strain, a diminishment of female authority, ranging from the earnest Catherine concerned exclusively with the home and the spiritual welfare of her community, to Joanna who played a supporting role in politics, to the frivolous Mary who is all show and remarkably little substance, hosting tea parties for both loyalists and revolutionaries.

Ms. Zimmerman is a vivid writer, and half a biography from her is better than whole ones from lesser writers. But a good deal of what she writes ought to be classified not as biography but biographical fiction.