The word "flapper" sometimes conjures the image of a slim, attractive, bob-haired party girl with a nonsensical, boop-boop-a-doop attitude, a string of pearls and a giddy love of giggle water. But, as Angela J. Latham points out in her book, Posing a Threat: Flappers, Chorus Girls, & Other Brazen Performers of the American 1920s, the flappers of the 1920s were part of a daring movement by American women to expand their freedoms and redefine what it means to be feminine.

It wasn't just about dress styles and sleek haircuts. Women then were pushing boundaries, from the chorus line to the seashore, that challenged the existing social mores and, in some cases, landed the women in jail.

The book is dry reading at times, but it's a deeply researched exploration of the time, when a woman's posture could be as controversial as the length of leg she bared at the beach or the sheerness of an outfit on the stage.

Latham explores the issue by closing examining the morals and attitudes of the day, looking closely at the laws governing somewhere, for instance, and the relatively brief shelf life of a Follies girl. She spends a great deal of time examining the reactions -- particularly in Chicago -- to a somewhat bawdy play, "Ladies Night in a Turkish Bath," which also pushed the envelope in interesting ways.

She makes it personal, too, by discussing in both the introduction and afterword the example of her grandmother, Nellie Latham, who defiantly bobbed her hair but concealed it by tacking on her long, carefully preserved braid to give her the appearance of conformity so she could keep her job as a schoolteacher. I wish Latham had found more examples like that, filling the book with any interviews or memoirs she could collect to carry that personal touch a little further.

As it is, the book is, as I mentioned earlier, pretty dry, sounding very academic in its prose but losing the all-important human element.

Latham also veers at times from her topic. Her implied outrage at the exploitation of young actresses in the '20s might be justified, but it feels out of place in this context. It almost feels like the grist for a separate book that was shoved instead into the middle of this one.

This book provides a lot of information, and there's no question Latham was expansive in her research. It's a shame she didn't stick more closely to the central theme and give a voice to some of the flappers she attempts here to champion.