Carson learned to write "C. Carson" late in life. It was very difficult for him. He made his mark on official papers, and this mark was then witnessed by a clerk. Carson easily spoke English, Spanish, and French. He could speak many Native American languages, including Navajo, Apache, and Comanche. He also knew the sign language used by mountain men. Very late in life, he learned to read to a certain extent, and to recognize his name when it appeared in print.