Research on learning in the undergraduate chemistry laboratory necessitates an understanding of students' perspectives of learning. Novak's Theory of Meaningful Learning states that the cognitive (thinking), affective (feeling), and psychomotor (doing) domains must be integrated for meaningful learning to occur. The psychomotor domain is the essence of the chemistry laboratory, but the extent to which the cognitive and affective domains are integrated into the laboratory is unknown. For meaningful learning to occur in the undergraduate chemistry laboratory, students must actively integrate both the cognitive domain and the affective domains into the "doing" of their laboratory work. The Meaningful Learning in the Laboratory Instrument (MLLI) was designed to measure students' expectations before and after laboratory courses and experiences, in both the cognitive and affective domains, within the context of conducting experiments in the undergraduate chemistry laboratory. The MLLI was pilot-tested and modified based on an analysis of the pilot study data. The revised, 31-item MLLI was administered online both at the beginning and end of a semester to both general and organic chemistry laboratory students. Evidence for both the validity and reliability of the data, as well as comparisons between general and organic chemistry students' responses, are discussed.