Tammi Van Hollander, LCSW, RPT-S, RST-C/T, is a highly respected clinical social worker, Registered Play Therapist Supervisor, and Registered Sand Therapist Consultant/Trainer with over 25 years of experience working with children, families, and individuals. She holds a Master of Social Work from the University of Pennsylvania and has received extensive training at The Family and Play Therapy Center in Philadelphia. Tammi is internationally recognized for her pioneering contributions to play therapy, attachment, sandtray play therapy, and sensory integration across age groups.

As a leader in the field, Tammi co-founded the World Association for Sand Therapy Professionals (WASTP), an organization dedicated to advancing sand therapy through research, training, ethical standards, and global community building. She played a pivotal role in introducing sandtray therapy to China, co-teaching the first-ever sandtray class in the country.

Tammi is also the author of Casey’s Greatness Wings, an attachment-based children’s book, and The Bibliotherapy Toolbox: 100+ Creative and Playful Story-Based Interventions to Help Kids Create Safety, Overcome Challenges, and Build Resiliency. She created Greatness Sticks and Greatness Cards to help foster resilience and self-esteem in children. Tammi conducts monthly virtual sandtray classes and is a sought-after international speaker, having delivered her first TEDx Talk in October 2023, titled Stories in the Sand: Healing Trauma, Anxiety, and Grief.