Already during embryonic development, the heart and the lung are thoroughly connected organs. Their interdependence allows our survival in the terrestrial environment by coupling cardiac output and gas exchange. The knowledge on developmental processes involving stem and progenitor cells is crucial to understand the onset of human cardiopulmonary diseases. The precise identification of various adult endogenous progenitors is still incomplete. Thus, caution should be exercised on newly available stem cell-based treatments until specific mechanisms of action are disclosed. The objective is to provide in the nearest future feasible and safer cell therapeutics for the complex pathological condition of human cardiopulmonary diseases. In this paper, we highlight the significant knowledge advancement concerning stem and progenitor cells in the cardiopulmonary field: from embryonic development to adult progenitors until early preclinical models for cardiopulmonary regeneration.