Who Would Have Thought It? (1872) is a semi-autobiographical novel written by María Ruiz de Burton. After a long period in which Ruiz de Burton's work was almost completely unknown, the novel was rediscovered by critics interested in the history of Mexican-American literature, and republished to acclaim in 1995. Yet Ruiz de Burton's life was not particularly typical of the Mexican-American experience, as she married a prominent US officer, Captain Henry S. Burton, in the aftermath of the Mexican–American War and became acquainted with many powerful people in Washington D.C. The novel reflects her ambiguous position between the small in number Californio elite and the Anglo-American populace, which formed the majority of the United States population.

It details the struggles of a Mexican-American girl born in Indian captivity, Lola, in an American society obsessed with class, religion, race and gender. The first ten chapters follow the central family in the years leading up to the start of the American Civil War and the attack on Fort Sumter (1857–1861), and flashbacks are meant to take the readers back further than that time line, such as the kidnapping of Lola's mother (1846). The last fifty chapters chronicle the events that took place during the Civil War (1861–1864). Each chapter focuses on a particular character and is told from an omniscient point of view.

María Ruiz de Burton was a native of the Mexican state of Baja California. During the Mexican–American War, Ruiz de Burton witnessed the American invasion of La Paz that began in 1846. In 1847, she met an American military officer, Colonel Henry S. Burton, in Baja. He had been ordered to invade La Paz to suppress a Mexican uprising where the Mexicans there gave little resistance.

When the war ended two years later, California was split into two; Baja California remained Mexican territory while Alta California became American territory. During the American Civil War, Burton served the Union Army. The two were married in 1849, a year after the Treaty of Guadalupe Hidalgo was signed. They lived in the newly claimed American territory and later moved to the East Coast, where Ruiz de Burton observed the economic, social and political turmoil wrought by the war and its aftermath.

Despite living in Eastern cities for a decade, as a Latin-American Catholic, Ruiz de Burton was considered an outsider in Union territory. She transformed her experiences living along the predominantly Protestant Eastern Coast, where Irish Catholics were poorly paid and discriminated against, into the novel Who Would Have Thought It?. The book was published anonymously in 1872; Ruiz de Burton feared that if it became known that a non-native English speaker had written the work that it would undergo greater scrutiny for grammatical errors.

The novel, written in chronological order, is divided into sixty chapters. The first ten occur during the years just before the Civil War (1857–1861), and flashbacks explain the way in which a fabulously wealthy Spanish Mexican named Lola came to stay with a New England family, the Norvals. The last fifty chapters occur during the Civil War (1861–1864).

The novel opens with Dr. Norval's return to New England from a geological expedition in the Southwest, accompanied by a ten-year-old girl, Maria Dolores Medina, known as Lola or Lolita, and trunks of supposed geological specimens that are actually filled with Lola's gold. He was appointed her guardian when he and his companions, Mr. Lebrun and Mr. Sinclair, rescued her from captivity. Because her skin was dyed black by her Native American captors, her arrival generates ironic disgust among the abolitionist women in the household, especially Mrs. Norval. She is horrified by the idea of Dr. Norval contaminating the racial purity of their home, despite his insistence that Lola is of pure Spanish descent and the dye will fade. Mrs. Norval demands that Lola work in order to pay for expenses; Dr. Norval objects and explains to her how Lola's mother, Doña Theresa Medina, gave him gold and precious gems she acquired while a captive of the Apache to finance Lola's care. Doña Theresa Medina asked him to rescue Lola so that the girl would be brought up as a Catholic. The Presbyterian Mrs. Norval is angered when she hears this but quickly reconciles her emotions when he shows her the trunks filled with Lola's fortune.

The second stage of the book proceeds in the style of a novel of manners but without losing the ironic treatment of the characters. Because of Dr. Norval's careful investment of Lola's gold, the family can live off only a small portion of the interest and still grow wealthy. However, the impending Civil War means that Dr. Norval's political sympathies, even though plainly pro-Union Democrat, made him increasingly demonized. The money he gives to his neighbors and family to raise companies for the Union army mean nothing and he is forced to leave the country. He makes sure to leave a will and careful instructions for the keeping of Lola's gold, however. During the war, de Burton shows the rise of the Cackles, neighbors of the Norvals who become unscrupulous and cowardly Senators and Generals for the Union. At the same time, the Norval men are taken captive or frequently injured in the line of duty. The honest efforts of Julian Norval and his aunt, Lavinia Sprig, to avert disaster or save lives are frequently stymied by the powerful and self-interested Cackles. Their efforts lead them into contact with the Secretary of War Edwin Stanton, who is left all-but-unnamed, and Abraham Lincoln, who is named but lightly caricatured. Lola, now in her late teens, has slowly been revealed as the owner of fantastic wealth. Before she comes of age and full control of her gold, however, the money is in the hands of Mrs. Norval, who plots with the hypocritical, sinful, sexual ex-reverend and duplicitous Major Mr. Hackwell to take it from the young girl. Hackwell contrives to trap Mrs. Norval by taking advantage of her husband's supposed death to secretly marry the supposed widow, despite knowing that her husband is still alive. He also secretly and dishonestly tricks Lola into an unwilling marriage. All this while, Julian Norval and Lola have pledged their love to each other, a love which threatens to take the money out of Hackwell's hands entirely. The machinations of Mrs. Norval and Mr. Hackwell come to a head when Julian returns from the war with news of his father's return, showing that the reports of the Doctor's death had been false.