There are currently no formal, standardized procedures for assessing speech processing and perception during infancy. This lack of tools makes interpretation of infant data challenging. This article describes how our clinical research center established listening-development criteria for infants with cochlear implants. The listening-development criteria incorporate programming, audiometric, and parent-report measures to estimate adequate audibility of the speech signal prior to the infants' inclusion in research protocols. This paper operationally defines the listening-development criteria, discusses its importance, and presents data from 10 infants who met the listening criteria on average after 6 months of device use.