Meet the Green Leaf team


Natalie Steffen, M.Ed.

Manager, Assessment Team

Licensed Educational Psychologist
Credentialed School Psychologist
CA License LEP 3587

Natalie has been helping children thrive in their academic setting for over 10 years. Whether in her former placements on school campuses or now here at Green Leaf, she works with children to identify their challenges and then collaborates with parents and educators to create a comprehensive treatment plan to fit the individual needs of the child. Natalie uses Cognitive-Behavioral Therapies to help children cope with anxiety, increase their confidence, make positive behavior changes, and develop their executive functioning skills.

As the manager of our assessment team, Natalie oversees the standardized assessments conducted at Green Leaf. She has a passion for using the most up-to-date, cutting-edge instruments to develop a comprehensive understanding of a child’s unique learning style and then uses these data to directly inform recommendations and interventions.


Sandra Concannon, L.M.F.T.


Licensed Marriage and Family Therapist
CA License #52807

Sandra Concannon has been working with children and families for over 10 years. She uses her vast clinical experiences and knowledge of evidence-based treatment interventions to help children overcome mental health, behavioral, and/or school related challenges. Her clinical work draws from Cognitive-Behavioral Therapy, the Attachment, Regulation, and Competency (ARC) model, and positive parenting methods. She works directly with parents to teach them how to respond to their child’s emotional experiences and develop their child’s healthy behaviors. Sandra is particularly passionate about helping children cope with anxiety and build confidence to achieve their goals!

Sandra Concannon is a member of our assessment team and is skilled in conducting Educationally Related Mental Health Assessments. She works with families and schools to implement the recommendations of these evaluations.


Lisa Gore, Ph.D.


Licensed Clinical Psychologist
CA License 30289
women | couples | health | workplace

Lisa Gore has been working in the mental health field for over 20 years. She has extensive experience with mood and anxiety disorders and maintains a specialty focus in behavioral medicine, the practice of integrating behavioral, psychological, and medical sciences. Lisa’s work in behavioral medicine covers areas such as the development of healthy lifestyle behaviors, acclimating to new medical diagnoses, coping with grief and loss, and treating anxiety and depression related to health conditions. She works with clients who are coping with chronic health conditions, including autoimmune disorders and chronic pain, and also helps people address functional neurological disorders. Lisa has a particular interest in women’s health and works with moms who have perinatal mood and anxiety disorders, as well as challenges in parenthood across the lifespan. Her breadth of experiences makes her particularly adept at helping individuals develop resilience to cope with the stressors of life. She is an expert in evidence-based treatments and uses strategies from cognitive-behavioral therapy, acceptance and commitment therapy, motivational interviewing, and mindfulness. Lisa sees clients ranging in age from late adolescence through the adult lifespan.

 Lisa is a part of our assessment team. She is an expert in conducting psychoeducational evaluations as well as psychological assessments.



David McCollum

Practice Manager

David oversees daily operations at Green Leaf with the goal of creating an easy, efficient experience for our clients. He is passionate about security and employs the highest standards to protect the privacy of our clients and ensure all processes meet and exceed HIPAA guidelines. He leverages technology to provide clients easier access to necessary information and ensure excellence in clinical care through cutting-edge data collection and analysis.


Jennifer L. McCollum, Ph.D.

Clinical Director, Founder

Licensed Clinical Psychologist
CA License PSY 23758

As the Clinical Director, Jennifer oversees the care of clients at Green Leaf. She is passionate about creating opportunities for families to receive access to exceptional services in a warm, friendly environment. She draws from her own broad clinical and research background, as well as outside experts in the field, to serve the needs of Green Leaf clinicians so they can maintain excellence in their standards of care!