Dairy Herd Improvement Associations, formerly called Cow Testing Associations, have operated in the United States since 1906 ; hence a report of the developments over the last 50 years constitutes a complete history of the work. Credit for organizing the first Dairy Herd Improvement Association in the U n i t e d States goes to a Danish immigrant, Helmer Rabild, and a small group of dairy farmers in Newaygo County, Michigan. Mr. Rabild knew what cow testing associations had meant to the dairy farmers in his native land, and he was convinced that a similar program would be of inestimable value to dairy F. J. Arnold farmers of his adopted country. As a consequence, he was instrumental in getting the first association organized. At the time, Mr. Rabild was employed by the Dairy and Food Division of the Michigan Department of Agriculture. The meeting that resulted in the organization of the first Dairy Herd Improvement Association in the United States was held on Sept. 26, 1905, and was attended by six or eight dairymen. After hearing Mr. Rabild explain the advantages of a production testing program, the group appointed a committee to set up the organization. The Association began operating in January, 1906. Thirty-one herds consisting of 239 cows were tested the first year. News of this new development soon spread. In Michigan the number of associations increased to four in 1907 and continued to grow until 1926, when a peak of 108 associations was reached. The first two states to follow Michigan's lead were Maine and New York. Each organized its first association in 1908. Five states got started in 1909, four in 1910, eight in 1911, three in 1913, seven in 1914, one in 1915, two in 1917, three in 1918, three in 1919, and one in 1920. The last state was Florida, in 1929. Except during the war years when supervisors were not available and during the depression of the 30's, the program grew steadily. On Jan. 1, 1956, 2,266 associations were operating (one or more in each state, Hawaii, and Puerto Rico). These associations were testing 40,984 herds consisting of more than 1,406,306 cows. Through the early years, the moving force behind D.H.I.A. work was the Dairy Division of the U. S. Department of Agriculture. The attention of the department was attracted to the organization in Michigan, and in 1909 promotion of the program became a federal project. Mr. Rabild was employed to head the work, and under his leadership the program was carried to all the states. In the states the organization and supervision of the program was under the direction or sponsorship of the state departments of agriculture or the state agricultural colleges, but by the time the Cooperative Agricultural Extension act was passed in 1914 the associations had become such a promising source of practical information that they were drawn into the state and federal extension programs.