Carl Rogers introduced key concepts to humanistic psychology, particularly the ideas of self-actualization and unconditional positive regard. His emphasis on the individual's subjective experience shifted focus from pathology to personal growth and wellbeing. Rogers advocated for a person-centered approach in therapy, where the therapist provides empathy and support, fostering a safe environment for self-exploration. By highlighting the importance of authenticity and the therapeutic relationship, Rogers contributed to the understanding of human potential and mental health, positioning humanistic psychology as a significant force in psychological theory.