ABSTRACT: Diagnosing mood disorders in chronic illness is problematic. Under-standing the value of individual symptoms in predicting depression is one approachto this problem. The contribution of individual symptoms to the diagnoses of majordepressive disorder (MDD) was examined in 82 patients with confirmed rheuma-toid arthritis (RA) and a control sample of ISO university employees. Comparisonsbetween DSM-HI and DSM-EQ-R rates of MDD were derived using the Inventoryto Diagnose Depression (IDD). It was found that cognitive-affective symptomssuch as dysphoric mood, acknowledgment of guilt, and suicidal ideation were themost efficient predictors of MDD. According to DSM-IH-R criteria, 16% of the RAsample met criteria for diagnosis of MDD, while 27% of the R A sample met criteriaaccording to the DSM-1H. RA patients reported that their arthritis affected theirmood at least occasionally. Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory disease thataffects approximately 1% of the population (Zvaifler, 1988). In addition to thepain and physical disability that are principal features of the illness (Potts,Weinberger, & Brandt, 1984), a variety of psychological factors has beenidentified as concomitant to disease(Anderson, Bradley, Young, McDaniel, W Frank et al., 1988; Rimon, 1974; Rimon & Laakso, 1984;Zaphiropoulos & Burry, 1974).The assessment and diagnosis of depression in RA has been questioned onclosely interrelated, conceptual, and methodological grounds. First, the few earlystudies citing the prevalence of depression in RA (e.g., Bishop et al., 1987;Zaphiropoulos & Burry, 1974) utilized instruments that were not designed todiagnose depression. These instruments contain many somatic items that arecommon to both depression and chronic illness (Turk, Rudy, & Stieg, 1987).Researchers in these studies typically have used self-report instruments such asREHABILITATION PSYCHOLOGY Vol. 36, No. 4,1991