The aim of this study is to describe and discuss the unique motivational characteristics of adult immigrants and refugees learning Greek as a second language, characteristics related to the concept of investment in second language learning, based on the results of a qualitative study carried out in non-formal educational settings. Seventeen (17) participants attending Greek lessons in non-formal educational settings in Athens, Greece, were interviewed through semi-structured interviews. The data obtained was analysed using thematic analysis. The students were asked about the reasons they are learning Greek and what motivates them to invest in studying the language. The results of the thematic analysis show that the main motives driving the participants to invest in learning Greek in the research settings were threefold: instrumental, integrative, and related to the L2 learning environment. Learning Greek was considered as a chance that could lead to greater job opportunities, empowerment, and greater integration into the host society. Additionally, the results highlight the fact that the atmosphere in the specific educational settings being very friendly and relaxed was very important for the participants and enhanced their desire to invest in learning Greek in the specific settings. Finally, the social aspect was also significant for the immigrants and refugees, who considered participation in the classes as a means of greater socialisation with both locals and other immigrants. The study highlights that non-formal settings are better suited to migrants/refugees’ learning needs and can promote the social inclusion of vulnerable groups and their integration into the host society.