Purpose: This study identifies factors related to job tenure among certified nursing assistants (CNAs) working in nursing homes. Design and Methods: The study uses 2004 data from the National Nursing Home Survey, the National Nursing Assistant Survey, and the Area Resource File. Ordinary least squares regression analyses were conducted with length of job tenure as the dependent variable. Tenure of CNAs was hypothesized to be motivated by the extrinsic rewards of their job, initial training and mentoring, reasons for being a CNA, organizational culture, and personal, facility, and market characteristics. Separate analyses were conducted for the overall sample and for CNAs who worked for the facility for more than 1 year. Results: Among policy-relevant domains, extrinsic rewards had the largest number of significant variables (4). Only 1 training and 1 organizational culture variable significantly affected CNA job tenure. Significant variables in domains not readily influenced by policy (e.g., personal characteristics and characteristics of the facility and surrounding market area) were often significant in both regressions. Implications: This study underscores the importance of the basic economics of job choice by low-income workers. Wages, fringe benefits, job security, and alternative choices of employment are important determinants of job tenure that should be addressed, in addition to training and organizational culture.