I put together 2 sheets - one I used as a guideline when interviewing contractors and another when interviewing their references. I didn't necessarily asked them every question. I can email you the finished sheets.

Contractor:
date
Phone number:
After hours No.
Registered in MA?
Contact:
Address:
Referred by:
How many years of experience?
How long in business?

How much experience with historical homes?
What is your specialty?
What sets you apart from the rest?

Tell them about my job: Converting 1820s house back to single
Items contractor may do or my subs:
Items we may do:

How many renovations have you completed?
How many completed similar projects?
How many kitchen designs have you completed?

What do you see as the important issues?

License
Type of work licensed to do:
Where are licenses held?
call the local building department to validate the number. Also, call the State Consumer Protection Agency to find out if the contractor had to prove financial stability, pass an exam, or just pay a fee for the license Check with your local building department or consumer protection agency to find out about licensing requirements in your area.
Is the company bonded and with who?
Can I have a banking and/or financial reference? Check financial stability. If the contractor is unable to pay for materials, labor, and overhead costs, the job could go unfinished.

What insurance coverage do you have? At a minimum, contractors should have
Workman's Compensation: Name of Co. and phone number
general liability (including property and personal liability), Amount, Name of Co. and phone number:
automobile insurance Name of Co. and phone number:
Call the insurance agency to confirm effective dates of the insurance policies.

What professional/trade organizations are you are a member of? Check membership standing in the organization provided.

Have you taken any classes or attended any trade seminars in the past 2 years?

Do you have any projects under litigation or complaints filed against you?
Any judgments against the company?

How do you handle this type of job?
Who will be assigned as a project supervisor for the job?
Will they be there every day?

Do you have employees or do you use subcontractors? Will you be using subcontractors on this project? If yes, ask to meet them, and make sure they have current insurance coverage and licenses, if required. Also ask them if they were paid on time by this contractor

How interested are you in this project?
Are you available and have capacity?
When can you start?

How long do you expect to complete this project?

Based on the project detail, what permits may be required?

May I have an itemized estimate on the project that includes materials, labor, overhead, and a time frame? The estimate should be in writing in order to compare it with the estimates you receive from the other two contractors.

What is your experience/track record with cost estimating or quotes?

Questionaire for references:

Contractor:
date
Phone number:
Reference:
What is your experience/track record with cost estimating or quotes?

 How did you find out about this contractor?
 How long ago did this contractor work for you?
 What was the quality of the finished project?
 Did the contractor recommend a contract, including a written estimate? If not, did you request a contract? Did the contractor balk at the idea?
 Did the project go over the original estimate? If so, by how much? What changes from the original project did you request? Did the contractor provide an acceptable detailed explanation?
 Did the contractor use a written change order form before making changes to the original estimate?
 Did the contractor stay on schedule and report to work in a timely manner?
 Did the contractor have a good attitude throughout the project?
 Did anything unusual or unsettling happen during the course of the project?
 How qualified were the workers and subcontractors?
 Did the contractor stay on-site to supervise during the project?
 How accessible was the contractor?
 Was the site clean and safe at all times?
 Would you recommend this contractor to your family and friends?
 Would you use this contractor again?

stretchad-I'm near you...in the Milwaukee area.
bostonpam- not the OP...but what a great list. Thanks.

I grew up in Milwaukee and went to Dominican and MU. I've been in Boston for 25 yrs now. I have these lists as word docs if anyone is interested. I took info from this and other websites. I also have a list of questions when interviewing architects. After 18 months of planning we were suppose to pull our permits 2 weeks ago but we're now in zoning purgatory :(

For each item that is listed as a general action, like "install recessed lighting," or "paint walls and ceilings," ask what supplies the quote includes, in terms of the particular specifications, or better yet, specify your own and ask them to quote on that. There can be huge variation in materials, and chances are the GC will go with what he can get at the cheapest cost -- which might be fine with you, but if it's not, it could lead to real problems down the road (and inflated "add-on" costs). I would also get a breakdown in labour v. supply costs, so that if you do change either of those components, the cost attributable to the change is clear. In my experience, lump sums leave the client in the dark.

I would also ask how he deals with changes that become necessary (or desired) as they arise. Ideally, the change and cost should be specified in writing.

Finally, talk about payment schedule. Make sure -- make absolute sure -- that there is a hold-back specified in writing, at least 10%.