In our data-rich world, there are strong calls for greater focus on data literacy as increasingly, 21st century jobs require some level of data literacy. Data literacy is inherently STEM integration, especially when working with real-world scenarios, as it requires bringing math and technology into the science classroom to interpret and engage with authentic data. Since teachers are often trained in one specific subject, they need additional support to accomplish STEM integration. In addition to subject matter knowledge of data literacy, this support must focus on the pedagogical content knowledge (PCK) required to implement and support student learning. This study sought to add an extra treatment to an existing STEM integration PD which focused specifically on teachers' PCK for data literacy. There is a major dearth of research on PCK for data literacy. Therefore, this study built on the limited research done on PCK for STEM integration and for statistics education to begin to develop an understanding of PCK for data literacy, an under-explored concept. This was an exploratory research multiple case study of four secondary school science teachers in an urban school district, who participated in the existing bioinformatics summer PD, then engaged in approximately 20 hours of workshop sessions focused on PCK development throughout the school year as they taught the bioinformatics unit. The initial findings show that there are unique components of PCK for data literacy that are different from those for science education. The participating teachers were able to surface their knowledge of student understanding of data and strategies for teaching with and about data to define a number of components of PCK that begin to build a framework for what PCK for data literacy might look like in a generalized form that could be used to support additional teachers seeking to growth their ability to teach with complex data. Additionally, strategies used in the extension PD, such as CoRes and video reflections were shown to offer support for teachers in their implementation of authentic data literacy in their classrooms. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]