Effective teaching practices, including the ability to make data-based decisions, are necessary to close achievement gaps. The purpose of this study was to investigate the effects of a collaborative, data-based decision making (DBDM) intervention on the quality of preservice teachers' DBDM. Participants were 45 preservice general educators enrolled in a teacher education course required for elementary teacher licensure. An experimental group design was used to investigate the effects of the intervention on the quality of preservice general educators' data-based decisions. Participants were randomly assigned to either the experimental condition, which was a 75-min, small-group, collaborative intervention on DBDM, or the control condition. Data were analyzed using a Mann Whitney U Test. The results showed that the intervention influenced the quality of preservice teachers' DBDM and that this collaboration influenced the confidence levels of preservice teachers with regard to DBDM. [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.]