A new senior high school was completed in 1975 leaving the Williams campus with 938 freshmen and sophomores.

A two-story classroom addition was added, and the rear entrance of the school received a facelift with a new ‘Warrior Center’ being constructed consisting of large windows and a roof made completely of skylights.

The school’s kitchen was expanded and the cafeteria received a fourth serving line at this time.

In 2013, another set of original classrooms and restrooms were gutted to make space for Plano ISD’s new Health Sciences academy.

This renovation created state-of-the-art classrooms for students interested in the medical field to learn and receive training and certification, complete with hospital beds.

When the school was originally built, the cafeteria, auditorium and gymnasium all featured large windows to let in natural light.

Only the cafeteria, band hall (which is now the orchestra room) and auditorium were air conditioned when the school was first built.

When the school was retrofitted to be fully air conditioned in the 1980s, drop ceilings had to be added in the original classrooms and corridors to hide HVAC infrastructure.

In some cases over the years, additional classrooms have been added wherever they could fit, whether or not it made sense from a design standpoint.

This has led students and staff over the years to dub the school ‘the maze’ or ‘the cave, because of its uncohesive design, low ceilings, and lack of natural light.

Once funding is secured for the second phase, the school will receive another interior facelift, with a goal of creating a more cohesive layout than the current “patchwork quilt” that years of additions and renovations has led to.

T. H. Williams, principal from 1961–1968, came to the district in 1936 as a math instructor and coach in the old Plano High School (now the Cox Building).

Thomas Howard "Bill" Williams (1902-1992) was honored as a teacher, coach, and principal who had given almost five decades of service to educating youths of Collin County.

[4] The Williams Warriors compete in these sports: Starting in the 2013-14 school year, Plano ISD has been offering a two-year health science program at Williams High School for freshmen and sophomores interested in pursuing a career in the health field.

[5][6] With a partnership with Collin College, students gain many opportunities: college credits, workforce certifications, working with real medical equipment and communicating with the local medical professionals (through field trips and clinical placements in skill-based classes.