TenniSpeak is a language company that teaches conversational English using tennis as a learning tool.

This method of language acquisition started with our immigrant father Dr. Henry DeYoung who came to the United States at the age of 15 in 1905. He did not know one word of English, had no money, and didn't know anyone in America, but later became one of the most educated communicators of the first half-century, culminating in his appointment as the Ambassador to Japan. He was fluent in Korean, Japanese, Classical Chinese, and English. He passed on this system of learning to his children who excelled in their chosen areas of science and liberal arts.

The youngest son Lee DeYoung was drawn to art and athletics, namely tennis, and he became a tennis pro. Lee was taught tennis by his brother Hank who played on a tennis scholarship at Denver University. With the help of his father and his sister who is a language professor, Lee developed a system of learning conversational English through tennis that is unlike any other language learning system in the world.