By 2050, Mexican Americans (MAs) will become the largest aged minority subgroup in the United States. Although older MAs often depend on family for care, no standard instrument is available to scale the motive for filial obligation. Building on previous work, the purpose of this study is to establish psychometric properties of the bilingual Mutuality Scale (MS) for use with MA family caregivers of older adults. A methodological design with a convenience sample is used. Through Principal Axis Factoring with Oblimin© rotation, a two-factor structure emerge—interaction between the caregiving dyad and reaction from the care recipient—which accounted for 63% of the variance in MS scores. Cronbach’s alphas are .87 in both cases and test–retest estimates across three weeks are r = .93 and .94, respectively. Despite needing further refinement, the MS shows potential to measure the motive involved in older adult care, which may be useful in designing culturally relevant interventions for the MA population.