Health and education are important determinants of economic success and general wellbeing both at the individual and macro levels. Yet individuals often do not appear to invest in these forms of human capital at levels commensurate with their importance. This is especially true in developing countries such as Bangladesh. This dissertation investigates interventions that have been taken to increase investment in health at the household level and education at the student level using the randomized controlled trial (RCT) design and presents simulations and recommendations for future RCTs. An intervention designed to change students' beliefs about the malleability of their own intelligence is shown to be a cost-effective tool for increasing learning. A novel intervention for handwashing is shown to be effective, while other novel methods backed by theory such as chlorine dispensers and disgust-based behavior change messaging are not. An optimal algorithm for assigning subjects to treatment that was developed by Atkinson (1982) is coded, field tested and simulations are provided to show the practically significant gains it can provide.