To develop a national system for occupational mortality several methods are being tested or explored in collaboration with other agencies: 1) updating the Continuous Work History Sample (CWHS) of the Social Security Administration (SSA) with Internal Revenue Service (IRS) information on occupation and with cause of death; 2) development of a program for state vital statistics offices to code occupation and industry on the death certificate, information now generally neglected; and 3) development of a large file of subjects of past Current Population Survey (CPS) samples for periodic collation with the National Death Index (NDI) to produce mortality tables by occupation, industry, and other demographic variables. The available CPS samples have been assembled and NHLBI has taken the lead in a project to link that CPS aggregate with the NDI. For the present and some time to come the CPS total is too small for effective work on cancer mortality. A mesothelioma study is underway in which the SSA is experimenting with the construction of employment histories from SSA records. This does not look promising from a cost standpoint. Efforts are continuing to obtain access to the IRS address file for medical research and to enable the SSA to create industry-of-employment cohorts for mortality studies. Success has been achieved in opening up the SSA address file to NCI investigators and it is believed that the way has been cleared for NIH investigator to obtain Social Security number (SSN) needed for mortality checks at SSA. Whether SSNs obtained from SSA may be used to obtain addresses from IRS remains uncertain.