Martial Arts Illustrated magazine called Randall G. Hassell "Shotokan's Great Communicator" and "The spiritual voice for a generation of karate-do practitioners." The Fighter magazine said Hassell is, "hands down, the world's finest, most authoritative karate-do writer."

Sensei Hassell is Chief Instructor of the American Shotokan Karate Alliance (ASKA), as well as Senior Editor of Tamashii Press, a traditional karate book and video publishing company, and a Founding Fellow of the International Karate Society (IKS). Sensei Hassell is a member of the first generation of Americans to pioneer Shotokan karate, introducing it to the St. Louis, Missouri area in 1961. He is a professional writer and editor who began karate training in 1960 and was a member of the Japan Karate Association until 1984. On September 1, 2002, he was voted President of the American JKA Karate Association (AJKA), an organization he helped to form in 1984.

As a teacher, he is known for his concentration on practical application of the fundamental principles of karate and for the application of kata techniques and principles to self-defense and kumite. In November, 2000, Hassell celebrated 40 years of dedication to Shotokan karate, receiving honors from many national, state, and local dignitaries.

While majoring in English Literature at Washington University in St. Louis, he began an intense, formal study of the history and philosophy of the martial arts in general, and karate-do in particular.

To date, this study has led to the publication of more than 100 articles in numerous periodicals around the world, and more than 28 books including:

The Karate Experience: A Way of Life;
Conversations with the Master: Masatoshi Nakayama;
The Complete Idiot's Guide to Karate;
Shotokan Karate: Its History and Evolution;
Karate Ideals;
The Karate Spirit (Selected Columns from Black Belt magazine);
Karate Training Guide Volume 1: Foundations of Training;
Karate Training Guide Volume 2: Kata--Heian, Tekki, Bassai Dai;
Samurai Journey (with Osamu Ozawa).

In addition to teaching at the ASKA Headquarters Dojo and at various YMCA's and school districts in the St. Louis, Missouri metro area, Mr. Hassell oversees the instruction and administration of thousands of students nationwide in ASKA and AJKA affiliated clubs, and he travels extensively, teaching, lecturing, and officiating.