This book forms an introduction into new or emerging discipline of “psychology of migration,” which is an interdisciplinary field of research, joining together diverse subfields of psychology (cultural psychology, social psychology, environmental psychology, health & clinical psychology, psychology of religion and spirituality) with anthropological, sociological and historical inquiry on migration processes (usually named “migration studies”). In the introductory part the borders of this borderline discipline are marked, important notions and the subject of inquiry defined (including theoretical models based on Authors’ experience, like MCC Model or The Five Changes Model), its main research themes presented altogether with prospective ways of discipline’s development, having in mind that there are many “white spots” yet to be covered in the field. The second part presents research methods applied in psychology of migration, dividing them, classically, into quantitative and qualitative, and providing examples of research projects in which exemplary methods and tools were used. Acculturation processes and their psychological analysis, forming one of the core themes in psychology of migration, are the main topic of interest in the third part. Next chosen research outcomes in the respect of mental health of migrants from an War Displacement Model as well as eco-cultural and epigenetic perspective are presented. The last part of the book covers issues of mutual relations between religion and migration, in the context of cultural and religious diversity. Some possible ways of the discipline’s development are delineated (e.g. psychology of spirituality and migration), and further theoretical models such as Five Metaphors of Religion and Migration or CBS (Culture-Bound Spiritualities) are presented. Finally some conclusive remarks on contemporary psychology of migration facing cultural and religious diversity in COVID-19 pandemic times are outlined, pointing at challenges the discipline will surely meet in the future.