Collaborating teachers need common planning time to plan instruction to teach students with diverse needs in their classroom. Teachers usually have limited common planning time or no time. It therefore became incumbent upon collaborating teachers to be mindful of how productively they use the limited planning time. This qualitative case study revealed data about how collaborating teachers in an elementary school in New York make productive use of their common planning time. The purpose of this study was to explore collaborating teachers' perceptions of what constitutes quality common planning time and how they utilized such time. Five pairs of general and special education teachers participated in the research. The data were gathered by means of interviews and journaling. The data were analyzed using thematic analysis and coding. The computer software, Microsoft Word was used to help code, sort and organize information. Data revealed 3 themes that crystalized the findings: common planning time for teachers, teachers' attitude towards teaching alone versus co-teaching, and the benefits and barriers to efficient co-planning. Findings of this study revealed that general and special education teachers' perceptions of quality common planning time include: adequate time to plan collaboratively, sharing ideas pertinent to student achievement. Several recommendations were made to ensure productive collaborative planning between co-teachers in elementary schools, including sticking to the topic during planning sessions. Recommendations for research included more gender diversity in the sample. This study will assist teachers, school administrators, and policy makers about the allocation of and the most effective use of teacher planning time which may influence student achievement. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]