What makes a great business partner?

So the question is pretty basic, what are good qualities in a business partner? As a young freelancer I want to expand my business into a much larger company and I know I will likely need to partner up with one or more people to make it happen.

1. What are absolute requirements?
2. What would be beneficial but not necessary?
3. Where would be a good place to look for business partners?

A partner ship is like a marriage. You need someone who complements you, and someone you can get along with well and someone you can trust, since you don't want to end up getting a divorce and having a custody battle over the child (aka business).

A founders agreement is essential. Unlike a prenuptial agreement, which might indicate a lack of trust or love, a partnership is a business, and therefore should always include the founders agreement.

Where do you find a partner? Start by talking with friends, and see if they know people that might fit what you are looking for. Also look into conventions and around business schools in entrepreneurship courses (since people that go to these courses usually look to start a business).

Good luck!

I have been using this list for quite a few years when selecting partners and people to work with. It has greatly benefited me in treating this process as objectively as possibly.

1. The person must share the core values of the business or organization.
2. The person should not need to be “managed”.
3. The passion to become the best at what they do.
4. Understand the difference between a job and holding a responsibility.
5. Would you hire the person if it were a hiring decision?
6. Does the person have a regard for rules, regulations and personal boundaries?
7. Professes a commitment to goals.
8. Integrity.

I totally agree with RonGa. There is a nice essay from Paul Graham about this.

And you know what they say: don't do business with family or with friends. Finding a partner is hard cause it takes a serious amount of commitment from him/her as it takes from you.

1. Absolute and most important thing is a sharing the same vision of the business you are about to run together. Without that, you will stuck in the mud.
2. If you have been working with potential partner before that would be very nice. This will give, for both of you, more confidence in each other and you will be able to set proper expectations.
3. Something I don't know yet for sure. So far, all my potential partners came through recommendations gotten from the people I've been working with, clients and friends. Only one turn out as a promising partner, but that partnership still needs to prove it self.

A person who behaves well and makes rational decisions under stress.
Each business has its ups and downs. If a business is hit with a nasty lawsuit, a key developer leaves, a major contract is lost - the last thing you want is your business partner to panic.

Something never mentioned is similar interests. Depending on your living arrangements this could be more important than you think. When I was looking for a business partner it never entered into my equation but now living with one another in a small location listening to obscure radio 12h every day, I'm extremely glad he has the same interests as I do. I'd go mad if I had to listen to pop music but equally, some would hate to spend hours on end listening to old school rap, 'tallo disco and electronica.

On top of that I'll echo some previous comments:
The person should not need to be “managed”.
The passion to become the best at what they do. - Does this person have values you hope/wish you had?
Would you hire the person if it were a hiring decision? - More than that, would you pay double?