Abstract: An automatic injection device for providing a injection is disclosed. The device includes a housing having a distal end operable by a user and an open proximal end for placement at an injection site. The device includes a syringe movably disposed in the housing. The syringe includes a needle and substance for injection. The device also includes a plunger that has a continuous length from a first end to a second end and includes an anchoring portion initially engaged with the distal end of the housing in a latched position. The device also includes a biasing mechanism to apply pressure to the plunger when activated and move the plunger towards the proximal end of the housing, and a firing mechanism assembly operable by the user to release the anchoring portion.