Researchers have studied negative effects of caregiving on a family caregiver; however, less is known about positive aspects of exchanging assistance for both members of a family caregiving dyad. In a previous naturalistic inquiry the author indentified a basis for studying caregiving interactions was a construct called shared care. The three components of shared care identified in the naturalistic inquiry were communication, decision making, and reciprocity. The Shared Care Instrument (SCI) was developed to measure the construct. The purpose of this study was to assess the psychometric properties of the SCI, and to assess its construct and criterion-related validity, A sample of home care family dyads (110 patients and 109 family members) returned usable survey questionnaires. Results indicated the Cronbach's alphas for the patient group for the SCI subscales ranged from .78 to .84, and .77 to .79 for family members. Factor analysis supported the underlying theoretical basis and factor structure of the SCI. Criterion-related validity was also supported. Therefore, the results of this study provide initial evidence for the reliability and validity of the SCI for use with family caregiving dyads. The findings support the need for additional testing of the SCI.