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). Significant indicators in a model of attrition include measures of mobiility and variables that correspond to the interviewer and interview process. There is evidence that surveys of longer duration and with higher frequency interviews experience higher attrition rates. The estimation results for a model of attrition and labor market behavior show little indication of bias due to attrition but there is some evidence that the labor market behavior of attritors and non-attritors is different.