The purpose of this article is to describe the development and testing during pregnancy and postpartum of a new instrument, the Cognitive Adaptation to Stressful Events Scale (CASE). The conceptual framework for the CASE is based on Taylor's theory of cognitive adaptation to threatening events using the dimensions of meaning, mastery, and self-esteem. A convenience sample of 202 primigravida women completed the CASE at six assessment points: 10 to 12, 20 to 22, and 30 to 32 weeks of pregnancy and 1 to 2, 8, and 14 weeks postpartum. Regression analysis conducted with CASE scores at each of the assessment points in relation to psychological symptom distress as measured with the SCL-90R Global Severity Index (GSI) indicated a strong relationship during each time period. Although replication with multiethnic, high-risk pregnancy and clinically depressed groups is needed, the CASE is a promising tool for examining the cognitive adaptation process occurring during pregnancy and postpartum.