The nation's Roman Catholic schools have labored for decades under increasingly adverse economic and demographic conditions, which have undermined their finances and sapped their enrollment. Today, researchers and supporters say those schools face one of their most complex challenges yet: the continued growth of charter schools. Since they first opened two decades ago, charter schools have emerged as competitors to Catholic schools for reasons connected to school systems' missions, their academic models, and the populations they serve. Charter schools, which as public schools are free of tuition, have their strongest presence in urban centers, traditional strongholds of Catholic education. Many charter schools tout attributes similar to those offered by the church's schools, such as disciplined environments, an emphasis on personal responsibility and character development, and distinctive instructional and curricular approaches. Those competitive pressures are coming into new focus with the release of research and analysis that attempts to quantify the extent to which Catholic schools' enrollment is slipping as a result of charter school growth--and seeks to offer strategies for how the church's schools might rebound.