The present study examined alternative measures of absence proneness related to organizationally-defined measures of absenteeism. A typical distinction among various types of absences is to separate medically-related absences from other types, since medically-related absences are believed to reflect random or unsystematic causes of behavior rather than voluntary choice behavior of the employee. The present study defined absence proneness as the degree to which individuals repeat their behavior. Three years of absence data for a sample of employees from one company were examined to discover the degree of absence proneness present in organizationally-defined forms of medically-related and voluntary absenteeism. In addition, a survey was administered to the sample to measure employee perceptions of work and non-work-related factors which were believed to be motivational determinants of absenteeism. A multiple discriminant analysis was developed in an attempt to classify employees into absence quartile groups based on their responses to a survey designed to measure motivational determinants of absenteeism. The classification results supported the view that medically-related absenteeism has motivational determinants related to employee work and non-work preferences. Implications for management are discussed.