Castells is a senior research associate in the Economic Mobility, Housing, and Communities policy area, where her research focuses on housing as a platform for improving economic mobility. She works on research design, project management, impact analysis, and data management to evaluate programs and policies that aim to improve the lives of families and individuals living in poverty. Castells is currently the project director for the Stepped and Tiered Rent Demonstration, which is testing two alternative rent structures for the housing voucher and public housing programs in 10 housing agencies as part of the Department of Housing and Urban Development’s (HUD) Moving to Work (MTW) Expansion initiative. She also directs the A Better Life (ABL) evaluation, which evaluates the implementation and outcomes for an economic self-sufficiency program in Massachusetts housing agencies that combines comprehensive case management, escrow accounts, community partnerships, and work requirements to help public housing residents achieve economic mobility. She was a lead analyst on the Jobs Plus Outcomes evaluation and is currently a lead analyst on the MyGoals for Employment Success program, an executive-skills-based workforce program that uses a highly structured, multi-domain coaching model along with financial incentives to help participants move toward economic self-sufficiency. Other recent work includes directing MDRC’s study of Santa Clara County’s MTW rent reform as part of HUD’s broader retrospective MTW evaluation and research design for the Rent Reform Demonstration. Before joining MDRC in 2007, Castells earned her bachelor’s degree in international studies from Middlebury College and a master’s degree in public policy from Johns Hopkins University.