National educational standards call for an increased focus on meaningful teaching and learning that is developmentally appropriate and helps all students reach levels of proficiency not only in basic skills but in higher order thinking skills and real-world application of skills. Among the recommendations for including real-world experiences in the community into students' education is service-learning. Service-learning uses community service experiences as an integral element of the teaching and learning process. The paucity of research and mixed findings on academic outcomes from K-12 service-learning led to an examination of the opportunity-to-learn conditions and practices in 271 middle-level schools in 16 states involved in documenting school improvement efforts in order to find out by whom and how service-learning was implemented. A secondary analysis was conducted of data from 2,164 core classroom teachers who participated in the High Performance Learning Communities Assessment during 1997-1998. Demographic information from 132,822 students in grades 6-8 were used to describe the socio-demographic characteristics of the schools where these teachers taught. Descriptive and correlational statistics were run to determine if relationships were evident between teachers' background and experience, attitudes toward educational practices, and classroom instructional practices. Multivariate statistics, including MANOVA and discriminant function analysis, were used to compute group differences in teachers' background and experience and use of the strategies of service-learning and standards-based instruction. Correlations and analysis of variance were computed to examine differences in which schools involved which students in service-learning. Findings suggested virtually no relationship between teachers' background and experience, attitudes toward educational practices, and classroom instructional practices. Although nearly all the teachers endorsed the strategies of service-learning, they were not implemented frequently. Discriminant function analysis revealed that teachers' professional knowledge of national and state curriculum standards and adolescent development predicted their use of service-learning strategies. The strategies of service-learning were also associated with more frequent implementation of standards-based practices for higher order thinking in literacy and numeracy. Correlational analyses indicated that students' background characteristics and their schools' urbancity were associated with opportunities to learn through service-learning.