The Borderline Personality Disorder Features Scale for Children (BPFSC) is currently the only dimensional measure specifically developed to assess borderline features in children and adolescents. Few studies have investigated this measure for its concurrent validity and concordance between youth self-report and parent-report versions. To this end, the current study had two aims: (1) to investigate the cross-informant concordance (youth self-report vs. parent-report) of the BPFSC; and (2) to examine the concurrent validity of the BPFSC by showing that youth scoring high on the BPFSC also show poor clinical and psychosocial functioning, as measured by a standard Axis I scale. A community sample (N = 171) of boys between the ages of 8 and 18 completed the BPFSC and a self-report measure of Axis I psychopathology. Parents completed a newly developed parent-report version of the BPFSC (BPFSP) and a standard measure of Axis I psychopathology to index clinical and psychosocial functioning. Findings confirmed expectations. Modest concordance between parent- and self-report ratings were found. In addition, youth with borderline features showed poorer clinical and psychosocial functioning in all domains, especially where externalizing problems were concerned. Concurrent validity and modest parent-child concordance were demonstrated for the BPFSC. The BPFSC and BPFSP show promise as dimensional measures to assess borderline features in boys. However, a criterion validity study is needed before the measure can be used.