The article deals with the problem of measuring public trust in modern Russian public institutions, and discusses the political practice of using the results of these measurements, socio-political and methodological problems of evaluation of trust as part of public opinion. The author proves the legitimacyof the question of how the traditional polling methods correspond to the complexity of the studied socialcategories and events, and justifies his own position on the example of credibility issue of the key statepolitical institutions. He demonstrates the inadequacy of routine approaches and presents alternative methods applied in three studies conducted by the INDEM Foundation in 1998‑2015. The authoranalyzes formal statistical characteristics of the relationships between the sets of estimates of confidencein various institutions and other characteristics of the respondents, and demonstrates the correlationbetween changes in the nature and structure of public opinion and changes in the political process. Itis established that after 2000 there was a transition from a diversified assessment of confidence in thevarious authorities to a rather monolithic one, as well as changes in the social framework of trust andseparation of the trust assessment from political demands to the authorities. The article establishes zonesof influence of conformism on the assessment of confidence in public authorities. Such confidence is notinstitutionalized due to its instability and lack of influence on political behavior. Lost is the additivecharacter of adjacent estimates of confidence, as well as the forecast potential of traditional survey results. Basing on this study, the author draws the conclusion about the need for new approaches to the study of public opinion.