This book is based on two open-access textbooks: Bhattacherjee's (2012) Social science research: Principles, methods, and practices and Blackstone's (2012) Principles of sociological inquiry: Qualitative and quantitative methods. I first used Bhattacherjee's book in a graduate-level criminal justice research methods course. I chose the book because it was an open educational resource that covered the major topics of my course. While I found the book adequate for my purposes, the business school perspective did not always fit with my criminal justice focus. I decided to rewrite the textbook for undergraduate and graduate students in my criminal justice research methods courses. As I researched other open- educational resources for teaching social science research methods, I found Blackstone's book, which covered more of the social science and qualitative methods perspectives that I wanted to incorporate into my book. As a result, this open-access textbook includes some content from both previous works along with my own additions based on my extensive experience and expertise in conducting qualitative and quantitative research in social science settings and in mentoring students through the research process. My Ph.D. is in Sociology, and I currently teach undergraduates and graduate students in a criminal justice program at Weber State University. Throughout my career, I have conducted and published the results of research projects using a variety of methods, including surveys, case studies, in-depth interviews, participant observation, content analysis, and secondary analysis of quantitative data. I have also mentored undergraduates in conducting community-based research projects using many of these same methods with the addition of focus groups and program evaluations.