Science, Technology, Engineering, and Math (STEM) education is currently commanding an ever-greater share of our national dialogue about education. Very few STEM initiatives focus on studies involving in-service teachers; most education research involves preservice teacher candidates. This researcher used a 54 question survey to examine in-service elementary teachers' science content knowledge and self-efficacy constructs. The instrument combines Enochs and Riggs' (1990) Science Teaching Efficacy Beliefs Instrument (STEBI) with the researcher's content knowledge instrument created from a northwest Florida school district's science textbook series. The researcher's instrument was created to access participants' science content knowledge so the results can be compared to science self-efficacy results from the STEBI. The results of this study show there is a statistically significant relationship between the teachers' science self-efficacy and science content knowledge. The researcher concluded that in order to increase in-service teachers' science self-efficacy, district and school personnel need to increase opportunities for teachers to improve their science content knowledge. [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.]