Career mobility is conceptualized in terms of the amount and bias of organizational, occupational, vertical and geographical movement. An operational measure is offered for the amount of mobility (not the bias) which permits comparative generalizations to be made about officials based on simple sampling procedures. For illustrative purposes, the amount of organizational mobility is measured for two samples of federal officials: David T. Stanley's sample (N = 557) of higher civil servants and a sample (N = 300) of foreign affairs officials. Several dichotomous background variables are included for both samples of officials including: age, rank, and education. Varying background characteristics is found to make only a small mobility difference for higher civil servants and a much greater difference for foreign affairs officials. Several speculations are offered to explain the political significance of the empirical findings, and a comparative typology of career mobility is developed.