References, bonding, insurance, experience with the roof in question (e.g., not all roofers here will work on a tile roof)

Fred Griffin nailed this one...

Check with the State for complaints filed, license issues, etc. 

   Next issue is the Price.

I'd say Jeff Dowler CRS has the right answer!

Jeff Dowler CRS has your answer.

References, referrals and reputation. Roofers tend to form new companies every few years! Few stand the test of time!

Licensed, insured, including workers compensation, and a list of recent clients

I would make sure they are licensed, bonded and insured plus obtain three references.

I'm having some roofing work done right now, and I'm using a guy who's done a great job for my clients over the years.

Insurance is a big one with me. 

References, business license, and insurance.

We had a new roof installed three years ago.  We used contractor who did a lot of business for other agents in our company.  Very happy with results

BBB and google. If they are crooks... certainly someone has complained.

I would expect to see SOME positive reviews as well. 

A mere nothing in google should be a red flag too... bad businesses can change their names.
So google the business, but also the principals too

Jeff Dowler CRS has the answer I'd give.

first and foremost, INSURANCE....  past jobs that can be viewed with homeowners to speak with for references...

References, insurance, specialty.

License status. Complaints filed. Lawsuits.  References. Verify yourself ... do not trust what one tells you.  

I have a lot of experience this - and I mean A LOT!

• Get references - and contact them, just don't get and not follow up
• Check their BBB rating - very very important to check first
• Insurance and license info - get it and research it FIRST!

References, written estimate and proof of insurance

Experience and reputation. 

The others have given good tips.

Licensed, Bonded & Insured. Then check references.

Shanna Hall - good question as I look at the other answers!

Not something that I am good at...

The better business BBB and how long they have been in business.

One thing I ask is how many nails they put in Architectural Shingles.  The supplier told me they need 5 nails each and less could void the warranty. I also always want felt paper under the shingles and no roof overs. Take those old shingles off and take the mess with you when you go.

Some issues are to get a WSIB clearance certificate, get a good contract, follow holdback laws and check references.  Also ask if they have had the appropriate training about working at heights - our government has been running ads for quite a while on this important matter.  There are also other issues to consider as well.

I found my roofer working for one of our premier builders.  He also has business of his own.

Experience, pride of workmanship & savvy. You won't know what really happened up there until another reviews it or it fails. Bad caulking, improper nailing, defective application and cheap materials plus minimum wagers! Hire the best for this once in a lifetime application. It pays for itself

Honesty & integrity ......I found several really good roofers and they never over charge our clients and give top notch service.

Making sure they are licensed and insured would be at the top of my list.

Shanna Hall A lot of good answers here.

Referrals from 3-5 years pryor

Experience and reputation. Are local builders and contractors using them?

Ask for references from past customers. I often check the Better Business Bureau for complaints too.