This study examined ways to improve fit and interpretive capacity of the M5-50, an IPIP-based personality instrument, using the Openness/Intellect model (O/I) given a history of poor performance of the M5-50 Openness scale (Author, 2013; Socha, Cooper, & McCord, 2010). With participants from Amazon’s MTurk (n = 305), theoretical models for the five-factor model, Openness as a 10-item single factor, and the O/I model were tested and fitted poorly After removing one problematic item, the O/I model showed acceptable fit. Findings indicate that the O/I model improved psychometric validity and interpretive capacity for the M5-50. The flexibility and open access of IPIP-based instruments such as the M5-50 makes the IPIP an optimal choice for instrument adaptation and construction in Latin America.