The 1970s and 1980s were difficult years for St. John the Evangelist. The school still did not have many basic facilities, including a gym, library, science lab, fine arts or technology programs, or Pre-K and Kindergarten classes. By this time, the football and cheer teams were also gone. These problems were part of a larger issue across the archdiocesan school system. While there were several elementary schools, there was only one Catholic high school—St. Pius X—and it could serve only about 500 students. For families at St. John the Evangelist, heavy traffic made the daily trip to the high school especially challenging.

At first, the archdiocese planned to build several new high schools, including one near St. John the Evangelist (one of those schools eventually became Our Lady of Mercy in 2000). Those plans were later canceled, and instead, St. Pius X was greatly expanded, eventually tripling the size of its campus.

Around the same time, St. John the Evangelist began receiving funding to improve the school itself. In the 1980s, air conditioning was installed across the campus. In the 1990s, the school added a gym, art studio, library, and new science and computer labs. The church building was expanded, making space for Pre-K, Kindergarten, and music classrooms. Hazardous materials such as asbestos, mercury, and lead were removed to make the campus safer. The school also changed its colors from red and white to the blue, gold, and white used today and updated its uniforms to their current style.

Meanwhile, major highway expansion projects improved traffic flow, making travel to St. Pius X much easier. In 1997, St. John the Evangelist earned its first National Blue Ribbon School of Excellence award, becoming one of the first schools in the archdiocese to receive this recognition.

These changes helped bring new stability and long-term success to both the school and the wider archdiocesan education system.

During this time, school safety was not a major concern, which was common across the United States. As shown in photos from the era, St. John the Evangelist, like other archdiocesan schools, did not have fencing around its campus. Schools generally trusted students to stay on school grounds and assumed that strangers would not try to enter. In the 1970s, some archdiocesan schools even allowed open campuses, where students could leave during lunch or other free periods. St. John the Evangelist may have followed similar practices.

Dismissal at the end of the school day was also very informal. When the final bell rang, students were often allowed to stay on campus, talk with friends, or walk around freely. There was no organized dismissal process, and students were expected to find their parents on their own. It was common to see children walking across parking lots or nearby streets without supervision. Safety patrols and the structured carline system used today had not yet been introduced.

In some ways, these relaxed rules gave students an early taste of the independence they would later have in high school.