Abstract: A delivery device for the controlled and continuous release of a useful agent at a functional rate is comprised of an erodible capsule housing a self monitored delivery device attached to a collapsed support. The device is comprised of a hollow container having a wall formed of a self-monitored release rate controlling material permeable to the passage of the agent by diffusion, or the wall is formed of a microporous material whose micropores are a means for holding a self-monitored release rate controlling medium permeable to the passage of the agent by diffusion. The device on its release from the bioerodible capsule in the environment of use releases an effective amount of agent at a functional rate over a prolonged and continuous period of time.