Origins and Development of Lifespan Integration

Lifespan Integration® (LI) was developed by psychotherapist, Peggy Pace, whose background in science, psychological theory, and trauma treatment shaped her curiosity about how lasting change occurs within the body–mind system.

During the 1980s and 1990s, she worked with adults who had experienced childhood trauma, abuse, neglect, and attachment disruption. She observed that insight alone did not always change the emotional, bodily, relational, and behavioral responses that continued to affect clients’ lives.

The Discovery of the LI Timeline

Peggy began using brief chronological memory cues to help clients move through the story of their lives—from early childhood toward the present. With repetition, she observed that the process did more than review autobiographical memories. The Timeline appeared to help the body–mind system recognize the continuity of development and experience that time had passed and life had continued.

The repeated experience of moving from the past into the present became central to Lifespan Integration. Rather than relying primarily on analysis or discussion, LI uses imagery, therapist attunement, and Timeline repetitions to support greater coherence and integration within the body–mind system.

From Clinical Discovery to a Psychotherapy Model

Peggy continued refining the Timeline and developing protocols for trauma, attachment wounds, developmental experiences, and ego-state organization. Her book, Lifespan Integration: Connecting Ego States Through Time, was published in 2003, and professional LI training began soon afterward.
As more clinicians used LI, it became increasingly clear that the model reached beyond the resolution of individual traumatic memories. It offered a systemic way of supporting regulation, attachment repair, continuity of self, and whole-person integration. Attachment theory, developmental neuroscience, implicit and explicit memory, neuroplasticity, memory reconsolidation, and complex-systems theory later provided additional language for understanding the changes clinicians were observing.

International Growth and Collaboration

Although Lifespan Integration originated through Peggy’s clinical work, its continued development has been collaborative. Trainers and experienced LI clinicians in different countries have contributed their clinical insights and experiences from their cultures, client populations, and professional communities. These contributions have helped expand LI’s theoretical framework, refine protocols, strengthen assessment and treatment planning, and improve how the model is taught.
LI Clinicians currently practice in: the United States, Eastern and Western Canada, France, Spain, Sweden, Switzerland, the United Kingdom, Malta, China, Netherlands, Austria, Ile de Reunion, Germany, Belgium, Guadeloupe, and Russia

The 2020 Restructuring

In 2020, Lifespan Integration underwent a significant restructuring of both its professional training program and its overall treatment framework. The revised structure brought greater consistency to how clinicians were taught to assess the organization and capacity of the client’s body–mind system, develop individualized treatment plans, select and sequence protocols, and understand the progression of therapy across the three stages of LI treatment.
This restructuring more clearly established LI as a comprehensive, systemic, and developmental psychotherapy.

The Formation of the Lifespan Integration Institute

The Lifespan Integration Institute was formed in 2023 to provide a lasting organizational foundation for the continued stewardship and international development of LI. Peggy has shared that the Institute grew from her desire to preserve LI as a coherent method of healing while allowing it to continue developing beyond her own direct leadership.
Purpose and mission of the LI Institute:

• Protect the quality, integrity, and consistency of LI training
• Support the development and review of protocols, manuals, and educational materials
• Establish professional standards for trainers, consultants, and certified therapists
• Encourage research and expand access to LI training internationally
• Support responsible outreach to underserved and trauma-affected communities