SSD (Society System Decontrol) is a straight edge hardcore (and later heavy metal) band from Boston. They released two records as SS Decontrol and then formally changed their name to SSD. As SSD they released two more records with a very heavy metal influenced sound.

Formed by songwriter/guitarist Al Barile (then a machinist at the General Electric plant in Lynn, Massachusetts and a student at Northeastern University), SSD started performing at smaller venues throughout the Greater Boston metropolitan area in the summer of 1981. The band quickly gained notoriety within the local music scene for intense, charged performances and the provocative antics of their core group of the "Boston Crew".

The original lineup was Al Barile on guitar, Springa (David Spring) on vocals, Jaime Sciarappa on bass and Chris Foley on drums. They released their debut LP The Kids "Will Have Their Say" in 1982. 

In 1983 they added second guitarist Francois Levesque and released the EP "Get It Away", widely regarded as their best record, and one that helped define Boston's straight-edge scene.

Like many hardcore bands in the mid-1980s, particularly in the Boston area, SSD began heading in a heavy metal direction. In 1984 they released the How We Rock EP  was rooted in the hardcore sound but exhibited overt heavy metal characteristics, such as a relatively high number of lengthy guitar solos. "Break It Up" LP in 1985. It had both feet planted in the metal genre, leaving behind all trappings of punk and hardcore. SSD broke up in November that year.

Barile went on to form Gage, Sciarappa joined Slapshot, and Springa went on to join Razorcaine and Die Blitzkinder. 

Scott Schinder, in his book Alt-Rock-a-Rama, described SSD as "The most important hardcore band to emerge from New England.