This article reports on a multi-method study of a high school course in data science, finding that students who take data science take more mathematics courses than those who do not, there are more under-represented students in data science than is typical for other advanced mathematics courses; that the students who take data science are more positive about a future in STEM and they tend to be older. Analysis of writing from the students shows that students are very positive about the course, appreciating the relevance of the content, the opportunity to investigate ideas, the chance to learn challenging, applied content, and the opportunity to think creatively. In an assessment of data and functions given to students in data science and Algebra 2 courses, the students in data science scored at significantly higher levels.