Background: The Next Generation Science Standards (NGSS) call for the integration of engineering content and practices in elementary science curricula, yet little is known about elementary teachers' preparedness to do so or their views on teaching engineering. Purpose/Hypothesis: The purpose of the current study was to explore K-5 teachers' perceptions about incorporating engineering in their classrooms as well as the perceived barriers for doing so. Design/Method: This study consisted of an online survey including a mix of selected response, Likert, and short answer items, followed by individual interviews and focus group sessions with a subset of survey participants. Descriptive statistics are reported for quantitative survey data. Open-ended survey questions as well as interview and focus group transcripts were inductively coded to identify emergent themes. Results: Many elementary teachers support the inclusion of engineering in the science standards for elementary grades. Teachers describe a lack of preservice and in-service training, background knowledge, materials, time for planning and implementing lessons, and administrative support as barriers to implementing engineering activities within their classrooms. Conclusion: While many elementary teachers support the use of engineering activities in their classrooms, there are numerous barriers preventing them from doing so. To ensure that NGSS are incorporated into elementary classrooms as they were intended, elementary teachers must be provided with the necessary training, resources, and support.