Purpose: This longitudinal study assessed student perceptions of sustainable design issues in the context of an accredited interior design program. Although literature exists documenting the integration of sustainable strategies into interior design curriculum, more analysis is needed to determine the impact of program experiences on students' attitudes. Design/Methodology/Approach: Over a four-year period, a questionnaire was administered to 245 freshmen in an introduction to interior design survey course and to 122 seniors enrolled in a professional practice in interior design seminar. In addition to statistically analyzing category responses between the two subject groups, the authors also looked for patterns in responses within each subject group. Findings: Results indicated that the seniors were significantly more aware of the term "sustainable design" than the freshmen were. Understanding the students' perceptions of more specific principles including life cycle thinking, environmentally and socially responsible materials sourcing and sustainable design practice required a more nuanced discussion. Although statistical significance of differences between the two groups was small to moderate throughout the survey categories, the seniors tended to be more deliberate in their responses. Originality/Value: This study is the first of its kind to conduct a longitudinal investigation of an interior design student body from freshman through senior cohorts regarding perceptions of sustainable design. Findings from the large sample size provide direction for interior design programs and form the basis for further study.