Topics covered: Randomized Controlled Trials (RCTs) are an important tool for tests of internal validity of causal claims in both health and social sciences. In practice, however, inattention to crucial details of data collection methodology can compromise the internal validity test. One crucial example is recruitment and retention of participants – though randomized to treatment, unequal reluctance to participate or unequal attrition from the RCT jeopardize the internal validity of comparisons within the RCT design. Another crucial example is the interaction of treatment and measurement – if the measures themselves change in response to the RCT treatment, then observed treatment and control differences may reflect these measurement differences rather than treatment differences. In both cases, specific tools from survey methodology can be used to maximize the internal validity test in the RCT design. This course will focus on the survey methodology topics most important for maintaining the internal validity of RCT studies and feature specific examples of applications to RCTs. One set of tools will focus on maximizing participation and minimizing attrition of participants. Core survey methodology tools for encouraging participation in both pre-treatment measurement and the treatment itself as well as tools for minimizing the loss of participants to follow-up measures will be featured. These tools include incentives, tailoring refusal conversion, switching modes, and tracking strategies. Links to RSD will also be made. A second set of tools will focus on measurement construction to reduce chances of interaction with treatment. These tools include mode options, questionnaire design issues, and special instruments (such as life history calendars) to minimize reporting error. Each portion of the course will feature examples applying each specific tool to RCT studies.