Our Team Members

At Yellow Bus ABA we love what we do, and hire those that share the same passion that we do. Check out our bios below to learn more about our team!


Chaya Geldwerth

Chaya received her Bachelor of Science at Mercy College in New York City. She earned her master’s degree in Education through Mercy College in New York City. She completed her coursework for board certification through Florida Institute of Technology and received her BACB certification in 2018.
Chaya has been active in the field of autism since 2004 and has a broad range of experience. She acquired her initial training in ABA working as a therapist in a center (age 3 and up) for children with ASD, then further expanded her knowledge by working at a residential facility with teenage boys with ASD diagnosis. She has provided 1:1 therapy, as well as consultation services, within the home, school and center- based settings.
Chaya’s passion lies in helping not only children acquire the requisite skills, but also to help the families integrate and actively participate in therapy. Her commitment and devotion to each patient and their families which are the hallmark of Yellowbus ABA, makes her an invaluable member of our team. Her skill, experience, and professionalism, along with her warm caring character maker her one of our most desirable therapists.


Harry Voulgarakis

Dr. Harry Voulgarakis is a psychologist and behavior analyst who specializes in the assessment and treatment of neurodevelopmental disorders. Dr. Voulgarakis hold an M.Ed. in Curriculum and Instruction for Arizona State University, earned an M.A. and PhD. in Clinical Psychology with a concentration in Neuropsychology from Fielding Graduate University. He completed his clinical training at the Seaver Autism Center for Research and Treatment in the Department of Psychiatry at the Icahn School of Medicine at Mount Sinai. While at Seaver, Harry conducted comprehensive diagnostic evaluations as part of the research assessment core, as well as private evaluations for a range of concerns including autism, ADHD, learning disorders, educational evaluations, and behavioral disorders.
Dr. Voulgarakis has expertise on clinical assessment of neurodevelopmental disorders and provides a range of assessments including diagnostic, neuropsychological, psychoeducational, and functional behavior assessments. He often incorporates other evidence-based treatments including acceptance and commitment therapy (ACT), applied behavior analysis (ABA), functional analytic psychotherapy, and mindfulness-based procedures. Dr. Voulgarakis enjoys working closely with families to provide system level support. He has specialized training and a particular interest in health psychology and works within a family systems model on health-related concerns and complex behaviors such as enuresis and encopresis, feeding disorders, sleep difficulties, communication disorders, and other severe behavioral concerns. In additional to clinical practice, Dr. Voulgarakis enjoys research and teaching and frequently presents at conferences as well as supervises graduate students in behavior analysis. He is currently an Assistant Professor of Child Study at Saint Joseph’s college in Long Island.


Estelle Parnes

Estelle Parnes earned her Master of Science in Special Education from Adelphi University in 2000. She completed her coursework to meet the instructional requirements set by the BACB through Penn State University in 2007 and earned her certification as a BCBA in 2009. Estelle has been working in the field of special education since 1993, in both school and home settings. She has taught courses on curricular assessment and behavior management at Mercy College in Brooklyn, NY, and has been a co-instructor for the BCBA coursework at the Florida Institute of Technology from 2012-2017. Estelle is currently the clinical director at YellowbusAba and continues to work directly with children in their home and at the center during social skills groups. She enjoys supervising future BCBA;s and sharing her excitement about the effectiveness of Applied Behavior Analysis.


Heather Greenberg

My name is Heather Greenberg and I have been a NYS certified School Psychologist since 2002. I started my career working in special education preschools that also had small, specialized classrooms that catered to students with Autism. It was at this early point in my career that I developed an appreciation for the demanding, rewarding and fulfilling nature of working with students with Autism. I continued working in the field but moved up to working with school-age students with Autism and other developmental disabilities at a non-public school. Through my work with older students, I obtained more specialized training in developing positive behavior support plans to address those behaviors that are obstacles to the learning process. Over the years, I've had the pleasure of working with many fine service providers including occupational therapists, speech therapist and physical therapists. But it was during my 3 years at the Delaware Autism Program as a behavior specialist that I received hands-on training and supervision by a team of Board Certified Behavior Analysts. After a break from the field to raise my two boys, I was thrilled to be connected with Yellow Bus ABA to continue my journey in working with extraordinary children leading ordinary lives. Over the years I've come to appreciate and highly regard the students and families I work with. It is deeply rewarding to get to see the world from a perspective other than my own.


Georgette Morgan

Georgette Morgan is a Board Certified Behavior Analyst (BCBA) who holds a Ph.D. in Applied Behavior Analysis from Teachers College, Columbia University. She has worked with a variety of children, including those diagnosed with Autism, in public and private school settings both as a teacher and a supervising behavior analyst. Georgette’s interests include furthering research on the incidental acquisition of language in young children with autism.


Susan Goodman

While working as a teacher in NYC public schools, Susan was selected by her principal to collaborate with Columbia University’s, CABAS program to bring Applied Behavioral Analysis to NYC schools. That began her love for “ all things behavioral” as well as her passion for training educators on the principles of behavior. She credits Dr. Greer and his CABAS program for making her a “ strategic scientist of behavior. “ Having learned from every student/ educator she has worked with, Susan draws from her 20+ years experience to bring powerful, real-life experiences to her workshops. When not working , Susan enjoys running, hiking and skiing with her family. She is currently pursuing a Masters Degree as a Reading Specialist at SUNY New Paltz.