Students benefit from collaborative learning activities, but they do not automatically reach desired learning outcomes when working together (Fischer, Kollar, Mandl, & Haake, 2007; King, 2007). Learners need instructional support to increase the quality of collaborative processes and individual learning outcomes. The core challenge is to find the right type and amount of instructional guidance to ensure that learners accomplish the intended learning goals. The purpose of this study was to examine the effects of different levels of instructional guidance on students' discussions and outcome in a simulation-based collaborative learning environment. Instructional guidance took the form of computer-supported collaborative learning (CSCL) scripts. A CSCL script is a set of instructions aimed at structuring the learning process. Scripts specify, sequence, and assign activities to collaborative learners (Weinberger, 2003). The main goal of this dissertation was to contribute to the continuing development of effective instructional strategies in computer-supported collaborative settings. A simulation-based learning environment called school efficiency simulation (SEsim), was employed which required learners to collaboratively develop solutions to a complex, authentic problem. SEsim had been designed and developed as a training and research tool that focused on the quality development of schools and included instructional materials, communication tools, and a simulation. The learners' assignment was to reduce the dropout rate of a school and thus to improve its efficiency. Each round of the game simulated one school year and the simulation provided immediate feedback about the learner's performance. Forty five students from two classes from a German gymnasium (a school that is equivalent to an American high school) specializing in pedagogy participated in the study. To experimentally examine the effects of the two different CSCL scripts, students were randomly assigned to two treatment conditions implemented during the collaborative learning task. Students operating under the precise instructional guidance (PIG) treatment condition were assigned roles throughout the discussion and received precise instructions regarding the number and nature of messages to be posted. The other groups, i.e., the general instructional orientation (GIO) groups, received more general instructions and students were not asked to represent a certain role. A mixed methods research approach was used in this study to explore how the scripts would impact students' discussions and the effects on individual performance. The primary focus was set on analyzing students' discussions to explore the scripts' effects on the learning process. The rich qualitative data allowed for obtaining a detailed understanding about the students' reaction to the given instructions. The secondary purpose was set on examining a different aspect of the research problem, namely the effects of the two scripts on students' performance. First, the students' discussions were analyzed to examine how the two scripts would impact students' conversations. Also, two groups, one from the GIO treatment condition and one from the PIG treatment condition, were selected for further analysis in the form of case studies. The purpose of the data analysis was to explore what was going on in students' discussions and to allow for comparison of the two treatment conditions (PIG and GIO) with regard to the nature of students' interactions. How closely the students discussed according to the given directions in the precise instructional guidance (PIG) script was also examined. Results showed that students from the PIG groups partially followed the precise directions and for the most part represented assigned roles. Structural differences between the treatment groups were discovered. Treatment effects reflected by differences in interaction patterns were found: Students in the GIO groups more frequently asked questions and exchanged superficial information whereas students from the PIG groups made suggestions supported by personal beliefs, experiences, and information from the learning materials. Furthermore, the data analysis revealed that the two groups from the case studies employed different problem solving approaches. Second, the effects of the CSCL scripts on students' performance were examined. An independent samples t-test was used to test the hypothesis that students with precise instructional guidance (PIG treatment condition) perform better on the posttest than students receiving general instructions (GIO treatment condition). Results showed that students in the precise instructional guidance groups significantly outperformed the general instructional orientation treatment groups regarding the first outcome variable, the simulation score. There were no differences regarding the second outcome variable, the causal model similarity score. Possible explanations for the results are discussed in relation to findings from related research. Limitations of the present study are presented along with its implications. Future research will include further development of the learning environment focusing on design of adequate assessment techniques and other factors, such as motivation, which may have an impact on students' performance. (Abstract shortened by UMI.) [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]