About Dr. Diana Mandeleew

Clinical Psychologist

Hello! I’m Diana

I have a collaborative, kind and empathetic approach. I want to hear and understand you. Together, we will explore your strengths, identify areas of difficulties, understand what is happening, instill hope, and figure out how you can move towards your goals and towards wellness.

I am a registered clinical psychologist. For the past 20+ years, I have been conducting psychological and psychoeducational assessments, providing ADHD coaching, psychotherapy and consultations to adults, adolescents and children with focusing issues and a wide range of social, emotional, behavioural and learning concerns. I collaborate with family doctors, psychiatrists, psychotherapists, educators, tutors, teachers, and other professionals. In addition, I have been supervising clinicians and psychoeducational instructors in several clinics, have been appointed to the College of Psychologists of Ontario’s Client Relations Committee and am teaching graduate-level Psychology courses at the Adler Graduate Professional School.

 I look forward to meeting you!

Dr. Diana Mandeleew, Psy. D., C. Psych. (she/her)


  • Doctor of Psychology in Clinical Psychology, Adler School of Professional Psychology (Adler University)
  • Master of Arts in Counselling Psychology, Adler School of Professional Psychology (Adler University)
  • Bachelor of Science with Honours, double major in Psychology and Biology, University of Toronto

Professional Associations and Memberships

  • Member of College of Psychologists of Ontario (CPO)
  • Member of Ontario Psychological Association (OPA)

Contact Dr. Diana Mandeleew

For more information or to book a free consultation


Psychological assessments, ADHD coaching and psychotherapy are conducted online, across Ontario. Psychoeducational assessments are conducted at our two testing centres (by appointment only).

York/Vaughan: 1520 Steeles Avenue West, Suite 101A, Vaughan, Ontario, L4K 3B9

Durham/Uxbridge: 29 Toronto Street South, Suite 107, Uxbridge, Ontario, L9P 1V9

In case of an emergency, call 911 or visit your nearby emergency department.