Purpose: This study was intended to adapt into Spanish and validate the short form of the Marwit-Meuser Caregiver Grief Inventory (MMCGI), an instrument for the assessment of levels of grief in caregivers of patients with dementia. Method: The adaptation was based on the cross-cultural equivalence model that included forward and backward translations, use of a bilingual committee, and a comprehension test. The validation study was carried out with 100 Puerto Rican caregivers. Results: Semantic and content equivalence were attained as judged by the bilingual committee. Conceptual equivalence was only partially supported as factor analysis failed to replicate the three-factor structure proposed for the original English version. A one-factor structure was the best suitable for the Spanish version. On the other hand, correlations of the total scores of this version of the instrument with measures of constructs expected to be related to grief supported conceptual equivalence. Discussion: The Spanish version of the MMCGI was found equivalent to the English counterpart except for its dimensionality.