During her husband's tenure she held the unofficial position of the second lady of the United States from 1913 to 1921.

[1] She became involved in charitable activities in Washington, D.C., and spent time working at the Diet Kitchen Welfare Center providing free meals to impoverished children.

Lois Marshall formed a close bond with the baby, who was named Clarence Ignatius Morrison, and offered to take him and help him find treatment.

[2][3] The Marshalls had been unable to have children, but they never officially adopted Morrison because they believed that to go through the procedure while his parents were still alive would appear unusual to the public.

Lois Marshall took him to see many doctors and spent all her available time trying to nurse him back to health, but his condition worsened and he died in February 1920, just before his fourth birthday.