Frank Jr.'s sister and co-author of the memoir, who draws from her experience as a department-store manager to bring depth to the narrative. Her perspective introduces themes related to women’s roles in mid-century America.

The patriarch of the Gilbreth family, known for his work in industrial engineering and motion study, applying these principles within the home. His character is depicted with a mix of discipline, humor, and affection for his family.

The matriarch, known as the "first lady of engineering," co-developer of motion study, and depicted as the calm and insightful complement to her husband's methods. After his passing, she leads both the family and their consulting firm.

Anne, Mary, Ernestine, Martha, Frank Jr., William, Lillian, Frederick, Daniel, John, Robert, and Jane are portrayed both as subjects of their parents' experiments and as a cohesive family unit navigating early 20th-century challenges. Their experiences illustrate the application of motion study in daily life, embodying the memoir's lighthearted yet observant tone.