The aim of the present study is to investigate the effect of laboratory applications based on scenarios on the pre-service Science teachers' science process skills. The sample group of the study consists of a total of 85 pre-service teachers (45 for the experimental group, 40 for the control group) who are in their first year in the Science Education Program in a state university. The model employed in the research study was a semi-experimental one having a pre-test, post-test experimental group and control group. In the experimental group, the experiments were conducted by the use of worksheets based on scenarios, whereas in the control group the experiments were conducted in the form of a close-ended experiment. In the study, the "Science Process Skills Test", which was adopted by Aydogdu (2006), was employed as a means of data collection. As a result of this study, it was found that the science process skill levels of the experimental group was significantly higher than those of the control group (p<.01). Accordingly, it can be argued that laboratory activities conducted with scenario-based worksheets are more effective than laboratory activities conducted with the use ofs close-ended experiment in terms of developing basic and integrated science process skills on the part of pre-service teachers. (C) 2013 The Authors. Published by Elsevier Ltd.