Aiming to relieve overcrowded schools operating on multiple tracks, the Los Angeles Unified School District (LAUSD) has invested more than $19 billion to build 130 new facilities over the past decade. District leaders asked researchers at Berkeley to estimate the achievement effects of this massive initiative--benefits that may stem from entering a bright, new school or from exiting an aging, even dilapidated facility bursting at the seams with students. Previous reports from the project examined how new schools and alternative schools have affected rates of student mobility and teacher turnover across LAUSD. By tracking thousands of students who moved from overcrowded to new facilities over the 2002-2008 period, the authors discovered robust achievement gains but also uncovered questions related to future deliberations. Key findings include: (1) The steady opening of new schools dramatically relieved overcrowding in elementary and secondary schools and set in motion a complex migration of students, both to new facilities as well as to a growing number of charter and pilot schools; (2) Significant achievement gains are discernible for elementary-school pupils who switched from an old facility to a newly constructed facility. On average, these "switching pupils" outpaced the average LAUSD student by a gain equal to about 35 additional days of instruction each year; (3) Achievement gains are most robust for elementary students who escaped severe overcrowding by moving to a new elementary school. Relative to the rate of learning for the average LAUSD student, this subset of students enjoyed achievement gains equivalent to about 65 days of additional instruction per year. Students migrating to certain new elementary schools experienced even stronger gains; (4) Across new elementary schools, the authors find no relationship between the per-pupil construction costs directly tied to classrooms and the magnitude of achievement gains. That is, pupils migrating to less-costly new schools saw achievement gains that were no different, on average, from those moving to more expensive new facilities; (5) After a new school opened nearby, students who remained in previously overcrowded elementary schools experienced modest gains, compared with the average LAUSD student; (6) Although new facilities featured slightly lower pupil-teacher ratios, higher shares of fully credentialed teachers, and lower teacher turnover, these features do not explain the steeper achievement growth of elementary students migrating to these new facilities. Additional research could uncover the deeper factors that explain the buoyant achievements results; and (7) The authors could only discern inconsistent and weaker achievement gains for high school students who moved from an overcrowded to a new school facility. Methodological Appendix is included. (Contains 5 figures, 3 tables and 3 endnotes.) [Additional funding for this policy brief was provided by the California Education Policy Fund.]