Within the modern history of social work, certain developmental periods in its professional ethics can be distinguished. In the theoretical introduction of this contribution, we explore selected ethical values and principles—namely, anti-discrimination, multiculturalism, and respect for diversity. These principles have become integral to the ethically sensitive practice of social work. The research section of this contribution presents a methodological overview of a qualitative content analysis of selected social work ethical codes. This analysis emphasizes the historical transformations of these ethical principles within international, Czech and Slovak contexts. The research findings offer insights that could inform the innovation of the Czech and Slovak ethical code of social work in the areas studied.