While the estimation accuracy of the strength of lap splices has been improving, the complexity of design for reinforcement development has progressively increased. This research study investigates the development of a simple and reliable design expression. Equations on development and splices of reinforcement in ACI 318-05 along with other design proposals are critically assessed in light of 203 unconfined and 278 confined beam tests where the splice region was subjected to constant moment. A simple design provision is developed that is based on a physical model of tension cracking of concrete in the lap spliced region. This new expression is shown to be consistent with current design practice, applicable to existing test results, and simple in application.