Lab components of undergraduate science courses typically have students complete highly directed cookbook-like laboratory activities. These experiences rarely engage students in a meaningful manner and do not accurately convey what the work of science entails. With funding from the Howard Hughes Medical Institute (HHMI), we have created more authentic science research experiences in a variety of undergraduate science courses, including introductory courses. Achieving this among the diversity of freshmen and sophomore science courses--each typically serving hundreds of students on our campus--required careful planning and adaptation. This article describes the many challenges we faced in our effort to create more authentic undergraduate student research experiences and the significant progress we have made in making such experiences more common for our students. Improvements in first-year science, technology, engineering, and mathematics (STEM) retention over the last 2 years suggest that the experiences may be having a positive impact.