A system and method for improved cumulative assessment provide for automatically, e.g., programmatically, determining an evaluation of two or more assessments including two or more related items in a cumulative manner. In one embodiment, an initial assessment including initial assessment items is administered at time T1 and scored to produce an ability estimate. At least one successive assessment is also administered and scored to produce an ability estimate. Selected ones of the administered assessments or included items are determined (“included assessments”), and the included assessments are scored to produce a simultaneous maximum likelihood ability estimate for the included assessments, for example, in view of all of the included assessments.