This study examined the experiences of 15 elementary schools in Washington state demonstrating relatively slow improvement on the reading and mathematics sections of the Washington Assessment of Student Learning. Since the passage of educational reform legislation in 1993, Washington has undertaken a systematic overhaul of its K-12 public school system, but some schools have not progressed as fast as others. The main source of data was a telephone interview with the school principal or a veteran classroom teacher (if the principal was new) at each school. Focus groups were held at a few of the schools. The study showed that schools that struggle to improve do not all struggle with the same barriers, nor do they approach school improvement in the same manner. The majority of the slow-moving schools were not effective at mounting an effective and integrated strategy of improvement. Instead, they adopted reform strategies in a slow and piecemeal fashion without the urgency and comprehensiveness that characterized their fast-improving counterparts. Schools were often limited by changes in leadership, weak leadership, a dysfunctional school culture characterized by staff resistance to change, and a slow consensus decision-making process that delayed the adoption of reform strategies. External forces also played a hand in the slow improvement of these schools. These forces included weak district accountability, weak district guidance, and inadequate resources or strategy. Teachers and school leaders identified other barriers to improvement and suggested assistance that would help overcome these barriers. Study findings also show that district- or parent-driven mechanisms for ensuring improved student performance are weak or nonexistent in most cases, and that state-imposed accountability is necessary to create real pressure for some Washington schools to improve. An appendix discusses study methodology. (Contains 23 references.) (SLD)