The use of the self-descriptive written composition in the study of self-perception is discussed. Self-perception characteristics and functions, resulting from self-descriptive composition and other techniques, are compared with those obtained by semi-structured interviews within the clinical method context. It is known that a good interview may provide more and better information than some written techniques do, but that's not the subject matter of the present paper. A congruency analysis of the dynamics and content aspects of self-perception data obtained by each technique as made. Examples are given. Possible causes of differences found in both methods results are discussed.