Initial testing has provided evidence that the concepts within the theory explain approximately 25% of the variation for a specific health behavior change and up to 45% of the variance when select characteristics of the participants (race/ethnicity and body mass index) are used as moderators (P. Ryan et al, unpublished manuscript, 2005).38,118 The ITHBC is being tested in a number of studies funded by the National Institute of Nursing Research (1R15NR009021-01A2 and 1P20NR0010674-01).