The utility of the self-report Children’s Anxiety and Pain Scale Anxiety subscale (CAPS-A) in comparison to the widely used, observer-rated Modified Yale Preoperative Anxiety Scale (mYPAS) in assessing anxiety in children undergoing day surgery procedures was examined. The CAPS-A test-retest reliability, concurrent validity with the Modified Yale Preoperative Anxiety Scale (mYPAS), and sensitivity to expected increases in anxiety at stressful times during the preoperative period were examined. Levels of observer-rated (mYPAS) and self-reported anxiety (CAPS-A) were obtained from 61 children (3 to 6 years) undergoing day surgery procedures. The CAPS-A demonstrated adequate test-retest reliability. Concurrent validity between the CAPS-A and mYPAS scores was poor. The CAPS-A failed to show sensitivity to the expected increases in anxiety at stressful time-points. Thus, an alternative scoring strategy for the CAPS-A was proposed (i.e., child’s refusal to point was scored as high anxiety). Post-hoc analyses demonstrated good concurrent and adequate convergent validity with the alternative scoring strategy.