With population aging, it is important to develop studies on psychological skills that can facilitate the task of caregivers of a dependent older adult. The Social Skills Inventory for Caregivers of the Elderly (SSI-CE) is an assessment tool for this purpose. Even considering that the instrument already has evidence of validity, the aim of this study is to seek additional evidence of validity for the SSI-CE. To this end, 533 family caregivers of older adults with an average age of 49.7 years were investigated by responding to the following instruments: Sociodemographic Questionnaire, Brazil Economic Classification Criteria, and SSI-CE. Initially, two factor models for the SSI-CE were compared (second-order and bifactor models). Then, analyses were performed for measurement invariance and sample heterogeneity of the SSI-CE in relation to the variables age, gender, presence of dementia in the elderly care receiver, and type of data collection (online or in-person). Finally, the instrument's reliability values were checked. After comparing the models, the second-order model was the most appropriate, as it displayed reliability values ranging from ω = 0.66 to ω = 0.89. In invariance analysis, variability was found for sample heterogeneity in the variables gender, presence of dementia, and type of data collection. In conclusion, the calculation of a global score for the SSI-CE is pertinent, with good evidence of internal validity. However, specific rules should be established, considering different sample characteristics.