How might a voluntary, high school summer reading program affect students' literacy motivation? A sequential exploratory mixed methods line of research attempted to answer this question. In study 1, after completing a summer reading program, 900 students from the 10th, 11th, and 12th grades provided written responses to the open-ended question, "What was the best thing about the summer reading program?" The researchers analyzed their responses with a phenomenological technique adapted from Moustakas (1994), yielding 11 motivational themes. In study 2, those themes guided the creation of a survey instrument, which then was administered to a different sample of 1600 students the following year. Student responses were analyzed statistically to determine the extent to which the new sample of students agreed or disagreed with the motivational constructs indentified in study one. Many of the qualitative themes were confirmed, however others were not. Also, differences among grade, gender, racial groups, and ability levels were identified. In study 3, a beta version of survey was scaled down and then administered the following year to a different sample of 1400 students to (1) determine the extent to which a new group of students agreed or disagreed with the motivational themes; and (2) determine if a more concise version of the scale would produce similar results.