Advances over the past few years in the field of Automatic Speech Recognition (ASR) have brought more attention to potential Bell System applications of this technology. Before reaching the point of ASR implementation, several human factors problems have to be overcome. This paper describes the central human factors issues, then summarizes the intial steps at Bell Laboratories in attempting to deal with those issues. Findings from observations of customers speaking credit card numbers to operators are described, followed by summaries of three studies investigating control of the speech of ASR system users.