A cardiac constraint device comprising a jacket of biological compatible material and an adjustment member. The jacket is adapted to be secured to the heart to snugly conform to an external geometry of the heart and assume a maximum adjusted volume to constrain circumferential expansion of the heart beyond the maximum adjusted volume during diastole and to permit unimpeded contraction of the heart during systole. The adjustment mechanism is configured to alter the internal volume defined by the jacket after the jacket is secured to the heart. The invention also provides a method for treating cardiac disease.