As part of the National Science Foundation Science Literacy through Science Journalism (SciJourn) research and development initiative (http://www.scijourn.org; Polman, Saul, Newman, and Farrar, 2008) a quasi-experimental design was used to investigate what impact incorporating science journalism activities had on students' scientific literacy. Over the course of a school year students participated in a variety of activities culminating in the production of science news articles for Scijourner, a regional print and online high school science news magazine. Participating teachers and SciJourn team members collaboratively developed activities focused on five aspects of scientific literacy: placing information into context, recognizing relevance, evaluating factual accuracy, use of multiple credible sources and information seeking processes. This study details the development process for the Scientific Literacy Assessment (SLA) including validity and reliability studies, evaluates student scientific literacy using the SLA, examines student SLA responses to provide a description of high school students' scientific literacy, and outlines implications of the findings in relation to the National Research Council's A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012) and classroom science teaching practices. Scientifically literate adults acting as experts in the assessment development phase informed the creation of a scoring guide that was used to analyze student responses. Experts tended to draw on both their understanding of science concepts and life experiences to formulate answers; paying close attention to scientific factual inaccuracies, sources of information, how new information fit into their view of science and society as well as targeted strategies for information seeking. Novices (i.e., students), in contrast, tended to ignore factual inaccuracies, showed little understanding about source credibility and suggested unproductive information seeking strategies. However, similar to the experts, novices made references to both scientific and societal contexts. The expert/novice comparison provides a rough description of a developmental continuum of scientific literacy. The findings of this study including student results and Generalized Linear Mixed Modeling suggest that the incorporation of science journalism activities focused on STEM issues can improve student scientific literacy. Incorporation of a wide variety of strategies raised scores on the SLA. Teachers who included a writing and revision process that prioritized content had significantly larger gains in student scores. Future studies could broaden the description of high school student scientific literacy and measured by the SLA and provide alternative pathways for developing scientific literacy as envisioned by SciJourn and the NRC Frameworks. [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.]