 Approximately half of the U.S. population experiences serious mental health problems during their lifetime, including 29 with anxiety pathology severe enough to qualify for an anxiety disorder diagnosis 1. Critically, more than two thirds of individuals struggling with a mental illness do not receive treatment 1. With this level of mental illness burden, it is clear that treating people one-on-one in an office setting will never meet the existing needs 2. There are many barriers to treatment, including costs 3, difficulties accessing evidence-based treatments in many regions 4, and associated stigma 5. Thus, there is a pressing need to consider alternative, larger scale approaches to delivering mental health services. Cognitive Bias Modification CBM interventions hold considerable promise as a way to meet these needs, especially for anxiety difficulties 6. These computer-based programs are designed to alter biased ways of thinking, such as a tendency toward negative interpretations, which cause and maintain anxiety 6. Because these programs do not require therapist contact and can be administered on any computer with an Internet connection, CBM holds promise as a cost-effective method that can be disseminated widely. However, while CBM for interpretation bias CBM-I has established efficacy when administered in-person in the laboratory 7, it now needs to be tested with broader populations using a web-based infrastructure to examine: a whether the program will be effective in a web environment, b whether the program continues to engage the targeted mechanism i.e., interpretation bias, c the feasibility of this delivery method, and d the modifications needed to adapt the program for the web in particular, to prime anxiety-linked negative thinking in an online environment, we test the effect of adding a guided anxious imagery exercise to prime feared outcomes prior to each training session. 