The article presents the Polish adaptation of Goldberg’s IPIP-BFM-50 questionnaire for measuring the five personality traits in the lexical tradition (Extraversion, Agreeableness, Conscientiousness, Emotional Stability, and Intellect). The adaptation procedure was carried out as a series of eight studies. Analyses were performed on a total of N = 7015 people aged from 10 to 83 (their mean age was 29 years). Reliability was assessed using Cronbach’s alpha coefficient. Factorial validity was verified in confirmatory factor analysis. In multigroup confirmatory factor analysis, measurement invariance between various research situations was verified. External validity was assessed by comparing the scores obtained using the IPIP-BFM-50 with NEO-FFI and NEO-PI-R scores. The results support the conclusion that the IPIP-BFM-50 is a measure with satisfactory psychometric properties, fit for use in scientific research.