Facts about the initial primary teaching in Salantai are controversial. One encyclopedia provides the year of 1630 when there was a parish school at the church. Another encyclopedia states the facts that the parish school had 14 pupils in 1801 and 77 pupils in 1811. It is also known that teacher Simonas Borisevičius worked in this school in 1831.
In the period of 1860–1905, a Russian governmental primary school operated in Salantai; however, most children learned to write and read in Lithuanian secretly, in private gatherings conducted by a director (so called ‘daraktorius‘ in the Polish fashion).
The Lithuanian primary school revived in 1905. At the same time, a primary school for girls of the "Saulė" society was established by the care of Prelate Pranciškaus Urbonavičius.
Between the wars, 9 primary schools worked in Salantai rural district. Two of them were in Salantai town. Lithuanians studied in one while Jews in the other.
On 1st September, 1942, a department of Skuodas Gymnasium was established in Salantai. On 1st September, 1943, the department becomes an independent school, Salantai Gymnasium. The first director of the gymnasium was Ignas Serapinas.
In the years of 1944–1952, Salantai Gymnasium, which was later reorganized into a secondary school, was directed by Jonas Daščioras, and from 1966 to 1989 its director was Juozas Norkus.
On 10th October, 1961, from the buildings scattered all over the town, the school moved to a new typical building with 880 seats.
In 1983, a 400-seat building for primary classes with a canteen and a gym was built.
On 27th July, 2006, Salantai Gymnasium was restored.
In March, 2021, the renovation works of the main gymnasium building were completed.
Since 1st September, 2020, Salantai nursery-kindergarten "Rasa" has been connected to the gymnasium.