The school was founded in 1945 as
Erith Technical School, Holly Hill Road: Principal E. Alec Wolf. Specialising in technical subjects such as Mechanical Engineering, Building Construction and Academic. The buildings (opposite the Seamans Home) were shared with the then Erith Grammar School. To facilitate the school's expansion in 1960–61, it was moved to its current site near
Bexley village, and its name was changed to
Bexley/Erith Technical School to reflect its new location. A few years later, this was expanded to
Bexley/Erith Technical High School for Boys; the name it maintained for several decades and giving rise to the school's common name,
BETHS or B.E.T.H.S. The school was later granted
grammar school status, and became known as
BETHS Grammar School for Boys until the most recent change to
Beths Grammar School. In 1995, the school was awarded
DfES Technology College specialist status, He retired from his position at the end of the 2014/15 academic year. Christopher Maxim became the new Headteacher in September 2015 and resigned at Easter 2017. Richard Blyghton was appointed as his successor. ==Notable former pupils==