A significant proportion of patients with a personality disorder do not benefit from treatment. Monitoring treatment progress can help adjust ineffective treatments. This study examined whether early changes in symptoms and personality dysfunction during the first phase of therapy could predict treatment outcomes. Data from 841 patients who received specialized treatment for personality disorders were analyzed. The study focused on whether changes in the Outcome Questionnaire-45.2 (OQ-45.2) symptom distress scale (SD), the General Assessment of Personality Disorder (GAPD), and Severity Indices of Personality Problems (SIPP) in the early phase of therapy predicted post-treatment personality dysfunction, as measured by the SIPP and GAPD. Early changes within a specific SIPP domain were the strongest predictors of post-treatment outcomes in that same domain. Early changes in symptoms significantly predicted outcomes in Self-Control, Relational Functioning, and Identity Integration, while the GAPD predicted outcomes in Self-Control and Social Attunement on the SIPP. For the GAPD, early changes on the GAPD itself, followed by early changes on the OQ-45 SD and the SIPP domain Social Attunement, were significant predictors. Thus, when it comes to personality dysfunction, early changes in a specific domain or measure are the best predictors of outcomes in that same domain. While the OQ-45 predicted some aspects of personality dysfunction, it should not replace disorder-specific measures. Additionally, the SIPP domains and the GAPD should not be used interchangeably to predict each other. In sum, considering these factors, monitoring early change can be useful in assessing progress in the treatment of patients with personality disorders.