Psychosynthesis is a transpersonal or spiritual psychology developed by Roberto Assagioli, a lesser-known contemporary of Carl Jung. Unlike psychoanalysis, however, psychosynthesis is not a perpetual analysis of the psyche and unconscious, but instead seeks to synthesize our conscious and unconscious layers to create inner harmony and importantly expand to higher consciousness states. The emphasis is on parts work, purpose, direction, and authentic will.
Psychosynthesis is a discipline to help liberate us from the unconscious cycles of our own minds and emotional body. It offers tools to navigate the human experience with both love and will.
"Psyche" meant "soul" in Ancient Greek, but we've separated the two and lost the connection to the latter. Psychosynthesis reclaims our soulfulness and reintegrates this into our very being for true mind-body-spirit based self-healing.
If you are familiar with Inner Family Systems, Psychosynthesis created an earlier framework that is very similar in terms of parts work. Psychosynthesis encompasses various other tools, however, and is a much deeper and spiritual based modality. I am not certified in IFS but have studied and taken courses on that practice as well.
At its most ambitious and for those on a spiritual path who are ready to detach, Psychosynthesis is a framework for Self-Realization.
You can read more about what Psychosynthesis is here.