Origin
The IPIP-NEO-120 is a 120-item public-domain measure of the Five-Factor Model of personality, developed by John A. Johnson (2014) from items in Goldberg's (1999) International Personality Item Pool (IPIP).
It was built as a freely available alternative to the proprietary NEO-PI-R (Costa & McCrae, 1992), reproducing that instrument's domain-and-facet structure without licensing restrictions.
Structure
The inventory measures the five broad domains — Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness — and, within each, six narrower facets (30 facets total), with four items per facet. This mirrors the NEO-PI-R architecture, allowing fine-grained personality description rather than domain scores alone.
Psychometric standing
Johnson (2014) reported the development and validation of the 120-item form (a shortening of his earlier 300-item IPIP-NEO), documenting its factor structure and convergence with the NEO-PI-R across a large internet sample. The IPIP items themselves carry extensive validation evidence assembled by Goldberg and collaborators (Goldberg et al
, 2006). The Five-Factor Model underlying the instrument is among the most replicated structures in personality psychology, recovered across languages and cultures (McCrae & Costa, 1997).