A Canadian passport or citizenship certificate, the current professional registration certificate, and an employer letter that sets out duties, dates, salary and reporting line. Supporting evidence of the credential's origin, such as a transcript, is worth carrying even when the licence alone satisfies the rule.
Build the file so an officer can read it in five minutes
The documents that decide a request are few, and their order matters more than their volume. Citizenship first: a valid Canadian passport is the cleanest proof. Then the credential: the registration certificate, in the applicant's current legal name, with the regulator's identifying number visible. Then the employer letter, which should say who the employer is, where the work will be performed, what the duties are in plain description rather than in internal job-grade language, how long the assignment runs, what the salary is, and who supervises the applicant. Anything else is supporting material: a transcript, a résumé, a copy of the professional appendix entry. Applicants who arrive with a bound folder of client testimonials and project photographs usually find that none of it is read, while a missing registration certificate ends the conversation.
Hypothetical example: Omar, a Canadian librarian, is joining a university archive in Oregon. Before travel, he asks the archivist to sign a letter that identifies the employer, assignment, duties, pay, supervisor, and expected end date; he then checks that the passport and academic records show the same name. That short review exposes whether the job is truly the listed profession rather than an unclassified records-clerk role. Canadian citizens may normally seek admission at a border inspection point or preclearance, while an employer may instead use Form I-129. Neither route makes a weak letter better. A missing signature, unexplained name difference, or duties copied from a generic posting can prompt questions that a neatly tabbed folder cannot answer.