As the title indicates, the purpose of this article is to document the changes that took place in the structure of gender, age, occupational activity, education and sources of income of Grudziadz residents during the period of People’s Poland. The purpose of the article was accomplished based on statistical data from successive population censuses. The research method comes down to analyzing the statistical data, comparing them using dynamic data reconciliation, interpreting the results taking into account the wider determinants that influenced the transformations. The entire study, in addition to the introduction, consists of six parts listed below: 1. The period of getting using the new system (1946–1950), where the characteristics of the residents are presented mainly in terms of labor activity and housing conditions. 2. The society of Grudziądz in light of the 1960 census. Attention was paid here to the gender structure, the age of the inhabitants, the professional activity of men and women by age groups. 3. Some social characteristics of Grudziadz’s population in the light of the December 1970 census. 4. The slow death of real socialism in Poland. In this paragraph, on the basis of the 1988 census, the demographic structure in 1988 is presented in comparison with the years 1960, 1970, 1978, the education of the population, professional activity, sources of income. 5. Households and families. 6. The process of change. This point is basically a summary and it synthetically outlines the changes. The entire study closes with conclusions.