Traditionally, adaptive behavior assessments have excluded the opinions and ratings of an individual assessed for intellectual disability/mental retardation (ID/MR). This exclusion has been justified via the clinical assumption that individuals with ID/MR are unable to provide valid reports of their own abilities. The current study directly investigated this assumption. Using the Survey Interview Form of the Vineland Adaptive Behavior Scales--Second Edition (Vineland-II), a standardized adaptive behavior measure, the current study compared the self-reported adaptive abilities of 28 individuals with Mild ID/MR with their direct care providers' (DCPs) ratings. Experimental measures designed to detect response acquiescence (yea-saying) and exaggeration of adaptive functioning deficits were also administered. Results indicated that when using the Vineland-II, resultant standard scores on all major domains of adaptive behavior were not significantly different. Age and sex effects were partially observed. The presence of yea-saying did not significantly predict concordance among dyad members. The experimental measure of response bias demonstrated relatively poor specificity and will require revisions to item content. Preliminary conclusions assert that individuals with Mild ID/MR should not necessarily be excluded from their own adaptive behavior assessments. Limitations and contributions of the study as well as future research directions are discussed.