Systems and methods are provided for reducing the effective volume of a cardiac ventricle. A ventricular volume reduction system may include a containment system or container body deliverable through a catheter into the ventricle, with the containment system or container body being fillable to occupy space within the ventricle. A ventricular volume reduction system may include a partition that sequesters a portion of the ventricle and separates it from the flow path of blood in the ventricle. Methods for reducing the effective ventricular chamber volume may include placement of the containment system, the container body or the partition within the ventricle.