The school opened its doors in 1964 and the student population at Downers Grove High School was split in two, half going to the original structure now named Downers Grove North, and half going to the new building. It has since undergone significant renovations to bring it up to date, including a $49.5 million voter referendum for the district in 2001. In the summer of 2008 the school embarked on a parking space expansion on campus, which had been plagued by delays. Despite several causes for postponement, parking lot adjustments were prepared in time to effectively start the 2008–09 school year. On Friday,
June 22, 2011 at around 8:30 pm, South High School received extensive damage to its outdoor sports areas during a two-minute
EF1 tornado: fences around the tennis courts were flattened, portable toilets and rows of bleachers were flipped upside-down as well as some fallen branches across the school's football/soccer field. In March 2018, the community surrounding the school voted to approve the Master Facility Plan (MFP), which laid out plans to completely overhaul both South and neighboring
North high school into modern learning facilities. Construction started at the end of the 2018–2019 school year, and was completed at the start of the 2021–2022 school year. The 2022–2023 school year saw the introduction of a new schedule, referred to as a "
Block Schedule". While far from the first implementation of this style, due to concerns from staff, students, and parents alike, the school board decided on a roughly half-and-half approach to its implementation. This was designed as both a trial run of this schedule type, and as a use for the various common spaces located around the school that were built during the MFP. ==Academics==