In July 1928, the present boundary lines of the school district were established with the consolidation of five common school districts, and the official name became Rural High School District Number One. The district, 88 square miles in size, became one of the largest districts in land area in Harris County. In 1938, the school district was renamed the Klein Independent School District after the name of the surrounding community. The growth of the area was very slow and steady; most of the residents were farmers, ranchers, and dairy farmers.

In 1966, the stage was set for exciting changes in the district when thousands of acres of land, covered with beautiful oak and pine trees, were purchased for residential construction. Developers found room to expand, a serene atmosphere of country living, and reasonable prices. Prior to this time there were no large city-like subdivisions located within the boundaries of the district which, because of its size and shape, is served by three different post offices: Houston, Spring, and Tomball.

In the 1970-71 school year there were 2,744 students enrolled in Klein schools. The current enrollment is in excess of 50,500 students in thirty-one elementary schools, nine intermediate schools, and four high schools. High School 5 is set to open in the fall of 2017. The Klein ISD has attracted new families from all over the United States of America and many foreign countries. The district has achieved an excellent reputation for academic, vocational, and extra curricular activities.