The purpose of this study is to search for the ways to diversify Outdoor/Environmental Education Program in the Nature Study Center(NSC), especially for the middle school students. For this study, various research methods such as literature review, questionnaire survey (448 students, 11 middle school teachers, 19 NSC staffs), interview and participant observation are used the process of this study consists of two steps. The first step is to define research questions through pilot survey and the second is to investigate the research questions, in the form of hypotheses through main survey. Nine hypotheses are formulated. Six are related with program elements (educational goals, student characteristics, staff resources, teaching methods, instructional resources, contents). three are related with program implementation process(preplan, implementation, post-evaluation). The hypotheses are tested and alternatives for program improvement are proposed. 1. Educational goals : Educational goals of NSC should be focused on Outdoor /Environmental Education and each NSC should specialize on its own theme. The objectives of every sub-program should be unified toward educational goals. 2. Student characteristics: The Outdoor/Environmental Education Program should reflect student characteristics: sex, urban/rural origins, normal/handicapped, number of visit and so on. 3. Staff resources : Provide qualified staff with professional knowledge and positive attitudes, reeducate staffs periodically, reduce management staff and increase teaching staffs. Provide permanent and well paid position, encourage and give opportunities and the middle school teachers to participate in program. 4. teaching method: Increase outdoor classes two way communication between teaching staffs and students adopt more open ended teaching method so that students can exercise coworks in small groups. 5. Instructional resources: Diversify NSC sites(mountains, coastal areas, urban areas and so on), teaching media (audio/visual equipments, graphic design of signs). Consider design for handicapped and integrate indoor and outdoor educational facilities. Plan nature trails with separate themes, allign nature trail so that it passes through diverse environments. 6. Content : Reflect characteristic site potential specialize on day or night program, on seasonal program, and on site specific social issues(such as interpreting of environmental damages around the NSCs). 7. Preplan: Get Information and know about visiting students in advance. Discuss with middle school teachers and adjust program weeks before visits if many or all of the students had already visited a NSC. arrange a visit to other NSC. Provide an introductory class for the teachers and students before they visit a NSC. 8. Implementation: During NSC visit and classes apply various and appropriate techniques to collect in formation for later evaluation. Improve NSC provided evaluation sheet so as to reflect student characteristic. Compare with formal education and investigate on effects of NSC program. 9. Post-evaluation: Formalize a post-evaluation process and organization. During the winter vacation, develop new programs based on the post-evaluationacation, for the next year. Also, have comparative evaluation meetings of staff from various NSCs during the winter vacation while there is no visitors and classes.