This paper analyzes attrition behavior in two major longitudinal surveys; the Panel Study of Income Dynamics (PSID) and the Survey of Income and Program Participation (SIPP). Attempts to explain attrition include demographic, location, and mobility indicators and variables that correspond to the interviewer and the interview process. The empirical analysis indicates that a number of variables that relate to the interviewer and the interview process have significant impacts on attrition in the PSID and the SIPP. There is evidence that surveys of longer duration and ones with higher frequency interviews have higher per wave attrition rates.