THE BASIC PHILOSOPHY UNDERLYING THE REGULATION OF FOREIGN WORKER IMPORTATIONS INTO THE UNITED STATES FOR AGRICULTURAL EMPLOYMENT IS THAT EMPLOYMENT OF SUCH WORKERS WILL NOT BE PERMITTED IF IT WILL HAVE AN ADVERSE EFFECT ON DOMESTIC WORKERS. THE "ADVERSE-EFFECT" POLICY HAS BEEN FOLLOWED SINCE THE ENACTMENT OF PUBLIC LAW 78 IN 1951 WHICH GOVERNED THE ENTRY OF MEXICAN NATIONALS INTO ARIZONA AND NEW MEXICO FOR SEASONAL EMPLOYMENT. THE TERM "ADVERSE-EFFECT" HAS NOT BEEN SPECIFICALLY DEFINED. RATHER THE CONCEPT HAS EVOLVED AS POLICIES HAVE DEVELOPED AND ACTIONS HAVE BEEN TAKEN TO COPE WITH SPECIFIC SITUATIONS. THE LEGAL BASES FOR TAKING ADVERSE-EFFECT ACTION AND THE MANNER IN WHICH THE POLICY OF THE DEPARTMENT OF LABOR HAS DEVELOPED ARE DISCUSSED. THE ADVERSE-EFFECT CONCEPT DEVELOPED THROUGH APPLICATIONS IN 1953, 1956, AND 1958 WHEN EMPLOYERS OF MEXICAN NATIONALS HAD TO INCREASE THEIR WAGES TO PREVENT DISCRIMINATION AGAINST DOMESTIC LABOR. IN 1959, SPECIFIC CRITERIA FOR JUDGING ADVERSE-EFFECT WERE ESTABLISHED AND FORMED THE BASIS FOR A WIDESPREAD ADVERSE-EFFECT PROGRAM DURING 1960-61. PUBLIC LAW 78 WAS EXTENDED, WITH INCREASING ADVERSE-EFFECT REGULATIONS, THROUGH DECEMBER 31, 1964. THEREAFTER, FOREIGN WORKERS COULD BE BROUGHT INTO THE COUNTRY FOR TEMPORARY EMPLOYMENT IN AGRICULTURE ONLY IN ACCORDANCE WITH PROVISIONS OF THE IMMIGRATION AND NATIONALITY ACT, WHICH CONTINUED ADVERSE-EFFECT REGULATIONS. THIS DOCUMENT APPEARED IN "FARM LABOR DEVELOPMENTS," AUGUST 1966. (WB)