"Contextualized assessment"-an ecological approach expanding the assessment more broadly to embrace all environments in which a child learns, works, plays and lives, as well as the child's specific experiences, abilities and skills within and across those environment, that proposed by Stump(1995) had been commonly used by many special educators. Through this model, various methods and tools are to be used for different objectives, procedure and settings, various kinds of formats, such as constructed response items, writing, oral discourse, exhibitions, demonstration in some situation, experiments, portfolios…etc, are also to be applied. Stump(1995) also proposed the Assessment Dimension System(ADS), which identifies seven dimensions of primary concern that assist determining which methods and tools are more appropriate to be included in the assessment battery. These seven dimension are (a)information uses (b)administration procedures (c)assessment findings (d)technical adequacy (e)performance demands (f)authenticity (g)alignment with curriculum content.The assessment of social skills is often not an easy thing, because social skills have quite a broad range and are so complicated that concerned with inner cognition, outer behaviors, personal behavioral management and other people's value judgment. So it will better to divided the assessment into several stages and apply the fittest methods according their each purposes. Sugai and Lewis(1997) summarized many kinds of assessment methodologies and illustrated their extent of purposes that can be addressed into a table(see table 1). Table 1 Overview of Social Skill Assessment Types Screening Problem analysis Curriculum selection and instructional development Progress monitoring-- performance Progress monitoring-social Teacher Rankings High Low Low Low High Others' Rating High Moderate Moderate Moderate Moderate Peer nomination Moderate Low Low Low High Behavioral Interviews Moderate Low Low Low Moderate Behavioral Role Plays Moderate Moderate Moderate Moderate Moderate Direct Observation- Frequency Moderate Moderate Low High Low Direct Observation- experiment manipulation Low High High High Low High/Moderate/Low = extent to which a specific assessment purpose is addressedProcedureThis study applied the notion of Stump(1995) and the suggestion of Sugai and Lewis(1997) on assessing the social skills of students with mental retardation. Five stages of assessment were taken for their each purpose, including screening, problem analysis, curriculum selection and instructional development, progress monitoring-performance, progress monitoring-social separately(see table 2). Table2 Description of purposes, methods, tools and subjects used in the each stagesStage Purposes Methods Tools Subjects Stage 1 Screening Peer Nomination Sociometric Questionnaire Students Teachers' Ranking Inventory for Assessing the Job-Readiness Skills of Students Placed in Alternative Classes Teachers, Teacher Assistants Stage 2 Problem Analysis Direct Observation ABC(Antecedent-Behavior-Consequence) Observation Form Students Stage 3 Curriculum Selection And Instructional Development Behavior Role Play Task Sheet Students Stage 4 Progress Monitoring - Performance Experimental Manipulation One-Group Pretest- Posttest Design Students Stage 5 Progress Monitoring-- Social Rating Scale Social Skills Rating Scales employers, Parents Interview Interview Outline employers, Parents Subjects12 students with mental retardation enrolled in the ChangHua special education school were selected as the target subjects. These students were organized as a mobile crew to work in an artificial leather factory that arranged according to their ITP. In addition, three teachers and three teacher assistants who responsible for this group, 15 employers and 5 managers who are worked together with the students and 12 parents of each target subjects, offer their opinions and rating about the social skills performance of the target subjects.12 students with mental retardation enrolled in the ChangHua special education school were selected as the target subjects. These students were organized as a mobile crew to work in an artificial leather factory that arranged according to their ITP. In addition, three teachers and three teacher assistants who responsible for this group, 15 employers and 5 managers who are worked together with the students and 12 parents of each target subjects, offer their opinions and rating about the social skills performance of the target subjects.Method and ToolsA sociometric questionnaire with 5 items and the Inventory for Assessing the Job-Readiness Skills of Students Placed in Alternative Classes adopted from Knight and Aucoin (1999).were employed at the stage 1 for the purpose of screening. An ABC Observation Form was used at the stage 2 for the purpose of problem analysis. At stage 3, the result of the stage 2 provide the direction for each student's needs of social skills training, then a series of lessons adopted from LCCE curriculum(Brolin, 1989) were used for instruction, each students were asked to role played the trained skills and .completed the task sheets. At stage 4, one-group pretest-posttest design was used to monitor the progress of the students' performance. At stage 5, social validity was tested by interviewing the parents and employers and asking them rating the performance of the target subjects