For 20 years, Christina Steinorth was happy to help one of her close friends with whatever she needed -- last-minute baby sitting, a drive to work when her car was in the shop, countless hours of free marriage advice (Ms. Steinorth is a licensed marriage and family therapist). She didn't expect anything in return.

When Ms. Steinorth and her husband decided to adopt a baby a few years ago, she asked her pal to write a letter of recommendation. The friend agreed enthusiastically, Ms. Steinorth says, but months went by and no letter arrived. She asked again and the friend apologized profusely, but still no letter. After several more months, Ms. Steinorth asked one more time. Her friend ignored her.

'I learned a very painful lesson -- that she wanted more from me than she was willing to give back,' Ms. Steinorth said.

Have you ever tried to make a withdrawal from the friendship bank, only to find your balance was much lower than you thought it was?

Friendship should be more than a series of tit-for-tat transactions: If I do a favor for you, then you will do one for me. Social psychologists call this view of relationships 'exchange orientation' and say it is more suited to business associates or other non-intimate relationships than to loved ones. In our close relationships, we'd like to think we give without expecting anything in return.

But that's just not reality. We do want something from friends -- emotional support, attention, a hand when we need one. Although we may not 'keep count,' we do want to be able to count on them.

Researchers have long known we feel bad about a relationship if we believe we're giving but getting nothing back. 'You need to perceive a balance between the costs and the rewards in a friendship or other close relationship, or there will be relational distress,' says David Henningsen, professor of communication at Northern Illinois University.

People who usually make an effort to help others, without regard to whether they will get something in return, are considered to have high 'communal orientation.' New research from the University of Toronto, published this month in the Journal of Social and Personal Relationships, suggests they are happier than people with low communal orientation.

To study this, the researchers had 232 people rate themselves on a scale of 1 to 7 on 14 statements such as, 'I often come to the help of others in need,' 'I believe people should go out of their way to be helpful' and 'It bothers me when other people neglect my needs.' The research subjects then completed surveys three times a week for one month, recording their levels of self-esteem, positive emotions, relationshipsatisfaction and love for humanity overall.

The results: 'Being a helpful person feels good and contributes to better relationships and greater satisfaction and self-worth,' says Bonnie Le, a Ph.D candidate at the University of Toronto and lead researcher on the study.

Even so, people with strong communal orientation aren't completely selfless. They do expect their friends will be there if they need them. The risk they run is they won't receive support, or they will even be exploited, by friends or loved ones with low communal orientation.

So what can you do if you tend to give a lot in a friendship and don't always get what you need in return? Start by rechanneling some of your giving. Volunteer for charity or help someone less fortunate. You'll enjoy the benefits of providing help and will be free of the expectation that you will receive something in return.

When making a new friend, pay attention early on to the other person's communal orientation. Does he ask about you and actually pay attention to your answer? Is she willing to do something you suggest doing, or work around your schedule? Not everyone is capable of giving at the same level. But if you are aware of who you are dealing with, you will be less likely to have expectations that won't be met.

Finally, realize that not all relationships can be fixed -- and that's OK. Ultimately, you need to decide who is worthy of your friendship. Learning to have more balanced interactions will help your future relationships.

Ms. Steinorth, who is 48 and lives in Santa Barbara, Calif., no longer speaks to her former friend. 'I thought, 'After all the little things I've done, all the times I've been there for you, I ask for just one thing and you can't do it?'' she recalls thinking. Her former friend did eventually write a nice letter of recommendation, she says, after Ms. Steinorth had her husband make the request. But by then the couple's application was no longer valid.

As a result of this experience, Ms. Steinorth says, she 'holds back' a little in her relationships, giving more to people who really need her assistance and can't reciprocate or even say thank you. Instead of cooking three dishes for family get-togethers, she cooks one and makes several casseroles for the homeless. And she volunteers at a Basset Hound rescue organization. She also pays close attention to a new friend's style of communal orientation.