ECA for Skilled Immigrants

Hi guys,

I am a Mechanical Engineer and would like my education qualifications to be assessed by an organization approved by CIC.
How do I choose my designated organization to get an ECA done?

Currently CIC website lists the following organizations.

•Comparative Education Service – University of Toronto School of Continuing Studies
•International Credential Assessment Service of Canada
•World Education Services
•Medical Council of Canada (professional body for Doctors)
•Pharmacy Examining Board of Canada (professional body for Pharmacists)

From the above ones I feel the last two are for medical professionals.

Can anyone shed some light on this. Any help much appreciated.

Thanks