She is best known as a co-author of the magazine series and the book The Woman Who Toils: Being the Experiences of Two Ladies as Factory Girls (1903) with a preface by US President Theodore Roosevelt, an influential example of social investigation.

[8] Marie Van Vorst found employment in a shoe factory in Lynn, Massachusetts, and a cotton mill in Columbia, South Carolina, under the alias "Bell Ballard".

[11] When the publisher saw the letter he asked Van Vorst to compile her magazine work on laboring women into a book and use the president's note for the preface.

[9] One part of the letter in particular caused a sensation among Americans who were not used to seeing any president address such issues as demography and birth control: If a man or woman, through no fault of his or hers, goes throughout life denied those highest of all joys which spring only from home life, from the having and bringing up of many healthy children, I feel for them deep and respectful sympathy; the sympathy one extends to the gallant fellow killed at the beginning of a campaign, or the man who toils hard and is brought to ruin by the fault of others.

But the man or woman who deliberately avoids marriage, and has a heart so cold as to know no passion and a brain so shallow and selfish as to dislike having children, is in effect a criminal against the race, and should be an object of contemptuous abhorrence by all healthy people.

[17] Some contemporary authors criticize Bessie and Marie Van Vorst for having a condescending attitude toward the working class, and indeed they themselves described working-class women as "degrading to look upon and odorous to approach".

[18] Sociologist Carolin Auer, in a 2000 essay on "social reportage", criticizes Bessie and Marie Van Vorst for the simulated reality they create.

Auer claims that the women's undercover investigation is nothing but a simulation of the reality as the researchers remain untrammeled by the economic, educational, and emotional ties which bind female factory workers.

[19] In 1908, Van Vorst wrote the book The Cry of the Children, in which she described child labor in wool and cotton mills in New Hampshire and Alabama.