He has been teaching ESL/EFL since 1973 both in the United States and around the world. The author or co-author of several texts (such as American Legal English), he is interested in practical application of theory and research. He was a co-founder of the ISLS during his Fulbright grant in then Czechoslovakia in 1989. Professor Hall has conducted working and training seminars from many governmental agencies and private corporations. He is currently a chairman of the ESP [English for Specific Purposes] Interest Section for International TESOL, the largest professional organization in the ESL/EFL field.