The aim of the article is to analyse the formation and functioning of the trade union movement in Poland during the period 1918-1939. The main research problem is the activity and development of trade unions as organizations of the mass labour movement, together with a determination of the main factors affecting the organizational forms and rules of functioning of these organizations. The issue of relations between trade unions and political parties and other social organizations is also presented. Another important issue is the presentation of the role of trade unions in shaping the socio-political attitudes of Polish workers, as well as the fulfilment by these organizations of social, educational, cultural and educational functions. The article uses descriptive and analytical methods appropriate for the investigation of social history.