s (1995) Early Maladaptive Schemas (EMS) are assumed to be highly stable and enduring beliefs that are responsible for the persistence and poor treatment response of a variety of clinical problems. EMS are now the basis for a growing number of specialized "schema-focused" treatments. However, the critical assumption that they are stable constructs remains largely unexamined and open to question. This study examined the long-term stability of Young's EMS in 55 depressed outpatients over a 2.5 to 5-year interval. EMS exhibited moderate to good levels of stability, even after controlling for severity of depression and neuroticism at both time points, and moderate levels of discriminant validity. A comparison of these results with existing literature revealed that the stability and discriminant validity of EMS are quite similar to the stability and discriminant validity of personality disorder features. Additional work is needed to examine the stability of EMS across greater fluctuations in mood and in different clinical populations. Our findings for the stability of EMS may be generalizable to the more general notion of core beliefs. Future work needs to focus on further theoretical development and improved measurement of EMS.