The Calgary Depression Scale (CDSS), a new tool developed by Addington et al. for the assessment of depression in schizophrenia, is presented in the article. As compared to the Harmilton Scale, CDSS is more specific to depressive symptoms in schizophrenia. Successive stages of the CDSS development and verification are discussed (i.e. item analysis, reliability and validity studies), and a Polish adaptation of the tool is presented.