There are at present no evidence-based interventions for marijuana use during pregnancy, despite its being by far the most commonly used illicit drug during pregnancy (particularly among African-American women), and despite growing evidence that it may have a range of long-term cognitive and neurobehavioral consequences. This R34 clinical trial planning grant therefore proposes the development and preliminary validation of two high- reach and mutually compatible technology-based interventions for marijuana use during pregnancy. The first, a theory-based, synchronous, and highly interactive computer-delivered brief intervention, will be based on an emerging knowledge base regarding key elements of efficacious technology-delivered interventions. The second intervention, a series of tailored text messages, will build on the rich literature regarding key tailoring elements. These interventions will be developed and refined with input from pregnant women who report active use of marijuana, as well as from health care providers. They will subsequently be tested-alone and in combination-in a pilot randomized trial involving 80 women actively using marijuana during pregnancy. This Stage I pilot work would set the stage for a confirmatory Stage II trial. It would also produce the first high-reach brief interventions for marijuana use during pregnancy. If effective, these approaches could have a substantial population impact on marijuana use among pregnant women, with potential for lifelong improved outcomes for both mother and child.