Tammi Van Hollander, LCSW, RPT-S, RST-C/T is a licensed 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 earned her Master of Social Work from the University of Pennsylvania and is internationally recognized for her innovative contributions to play therapy.

Tammi is the author of Casey’s Greatness Wings, The Bibliotherapy Toolbox: 100+ Creative and Playful Story-Based Interventions to Help Kids Create Safety, Overcome Challenges, and Build Resiliency, and her newest children’s book, The Loving Stop Sign: A Story About Connection, Not Correction. She is also the creator of Greatness Sticks, a playful therapeutic tool designed to foster resilience and self-esteem in children.

A leader in the field, Tammi played a pivotal role in co-teaching the first-ever sandtray therapy class in China, helping introduce this transformative modality to the country. She is a founding board member of the World Association for Sand Therapy Professionals (WASTP), an organization dedicated to upholding the integrity of sand therapy through research, training, ethical standards, and global community building.

Tammi is a sought-after international speaker and delivered her first TEDx Talk in October 2023, titled Stories in the Sand: Healing Trauma, Anxiety, and Grief. In August 2025, she served as a keynote speaker at the first-ever National Play Therapy Symposium in Africa, sharing her expertise in connection-based play and sandtray therapy with professionals from around the world.