The Therapist's Personal Style (TPS) integrates the professional's dispositions, traits, and attitudes in their clinical practice (Fernández-Álvarez & García, 1998). Although initially considered a stable construct due to its link to personality, its dynamic nature is now debated (Casari, 2019; Fernández-Álvarez et al., 2012). This study evaluated the extent to which personality explains the variance of the five functions of PST. The abbreviated PST questionnaire and the Big Five Inventory were administered to 78 psychotherapists matched in experience and theoretical framework. The results show that personality explains 11% of the variance (R²=.11), with Openness to Experience being the most predictive trait (β=.23, p=0.03 for attentional function; β=.23, p=0.02 for expressive function). These findings support the hypothesis of EPT as a fluctuating construct, possibly influenced more by dynamic variables such as training and deliberate practice than by stable personality traits.