This report delves into the multifaceted field of psychology, particularly its application within health and social care settings. It begins by comparing various psychological theories of lifespan development, such as behavioral and cognitive theories, and their relevance to specific life stages, including infancy, early childhood, and adulthood, with a detailed examination of Erikson's psychosocial stages. The report then explores the impact of social and biological factors on human behavior, emphasizing the influence of culture, religion, education, genetic characteristics, and hormonal changes. Furthermore, it highlights the significance of social roles in the context of health and social care, stressing the importance of improving equality for patients with psychological disorders and promoting preventative measures. The report also discusses the application of psychological theories to individuals experiencing stress, behavioral disturbances, and mental health disorders, and the use of psychological principles to affect behavioral change, ultimately enhancing the understanding of relationships. The report concludes with a self-evaluation and references.