For better or worse: look no further for a business partner. You may already have a perfect match—your spouse.

Meeting someone special, falling in love, getting engaged, planning a wedding, living the everyday reality of a marriage. Millions of Americans have taken the plunge until death do us part. In fact, according to Census data, there were 57 million married couple households in 2003. These couples said vows promising to love, honor and cherish. But for some of these couples, there has been one additional wedding caveat: They've decided to start a business with their spouse.

And while it is often said that marriage is hard work, what happens when you decide to combine the work of your marriage with the work of starting a new business? First, "[Don't assume], 'Oh, we get along well in our family life, so we'll get along well in our business together,'" says Bob Murray, who, along with his wife, Alicia Fortinberry, runs Fortinberry-Murray Consulting, a coaching business that specializes in helping people build solid relationships within a business setting. "Running a business together and being a family are two different things," he says.

Adds Fortinberry, "You want to make sure that you're working together because you enjoy being together, the relationship is pleasurable for both of you, and it gives you so much that you want to extend your relationship from home to work." It can be a fun ride, if you're meant for it.

Courtship and Engagement

Deciding if you're ready to start a business with your spouse mirrors the choices and self-examination you endure when you're first dating. Says Murray, "[Ask yourself], Do I want to be with this person 24/7?" Can you see yourself working side by side? Are your visions for the future the same?

Adds Fortinberry, "Do you share the same values and vision? That should be discussed, and if you can't come to a clear agreement, then that's a danger signal."

Entrepreneurs Todd and Jan Haedrich, founders of My Flat In London, a high-fashion design company and manufacturer of handbags, accessories, clothing, and body products like lotions and lip balm, could definitely see themselves working together all the time. Jan, 35, had a fashion-industry background and got the idea after creating a handbag for herself and getting stopped on the streets by people asking where she got it. Todd, 34, saw how hard she was working creating the bags at home, and the pair realized they had the makings of a much bigger business on their hands.

Officially founded in 2002 in Boston, the company has since moved to Frenchtown, New Jersey. Jan conceived the My Flat In London moniker after her time spent living abroad, and she still credits her design inspiration to her many travels--accompanied by her husband, Todd, of course.

Still, the key is that the Haedrichs have the same vision for My Flat In London: They see it as a luxury lifestyle brand. And they detailed that vision during the planning stage of the business when they consulted a third party for an objective outside opinion. "We had a number of conversations with Jan's brother [separately]," says Todd, who saw the value of feedback from an unbiased family member. "He was a person to bounce ideas off of without fighting with each other--and it helped us get started on the right foot." That good start has gotten the company's products into stores like Nordstrom, pushing yearly sales to $4 million.

If the Haedrichs' marriage and business is a good example of what other married entrepreneurs should aspire to, reverse those traits to learn what not to do, says psychologist Linda Miles, co-author with her husband, Robert Miles, of The New Marriage: Transcending the Happily Ever After Myth. Don't be critical of each other--and don't be dismissive or contemptuous of your partner. "Can you [both] attack problems and not the person so that the marriage doesn't suffer?" she asks. Miles also urges being very honest with yourself in the planning stage. Ask yourself if you'll be equal partners and if you're willing to share whatever glory and success your new entrepreneurial venture brings--you know, the "for better or worse" part of your vows.

Planning the Wedding

Once you determine that you can start a business with your spouse, you have to go into planning mode. A business plan is vital for any business, and for married couples starting a business together, determining what roles each of you will play in the business is essential. Just like when you planned your wedding--everything from a budget to a guest list--this is the time when you delineate everything from your respective roles in the business to your financial plan. "Work out exactly what the roles are going to be within the business," says Murray. "Most arguments are around roles and finances--you have to sort out the 'who does what' within your business."

Choosing business roles based on each partner's strengths is exactly what helped Stephanie and Mark Healy, both 36, become successful with Vente Inc., their database marketing company in Omaha, Nebraska. Started in 1999, Vente specializes in collecting opt-in market research and consumer information and selling it to marketers. Stephanie covers the sales and marketing side, while Mark handles the technical compliance side. "We really have two different skill sets," says Stephanie, who recalls some advice they received at a business event they attended: "When couples work together, one needs to say, 'I'm leading this area in the company,' or 'This is where I fall under.' So we had to make that distinction."

Communicating each person's needs and wants in the business is another fundamental of couple entrepreneurship. "The backbone of any relationship is understanding what each of you needs and being very clear on that," says Fortinberry. "When [couples] are working closely together, you need to articulate yourself to the other person." Be clear about what you need, and make sure it's an action your partner can actually complete. If your partner isn't wearing suitable clothes for a business meeting, for instance, communicate that your need for the business is to present a professional appearance, and that your partner can do that by stepping up his or her attire.

The Healys have gotten the communication message. "You'll have disagreements over what direction to take, but there's really no one other than your spouse who you can speak to and let know exactly how you feel," says Mark. "It is an advantage, being able to speak with your spouse openly and honestly about 'This decision needs to be made' or 'We need to go in this direction.'"

Adding to the challenge, the Healys, like all of the other married couples interviewed, have children. Having delivered their second baby almost immediately after closing their second round of funding, Stephanie and Mark know the difficulties of raising a family and starting a business simultaneously. "It's hard to turn [the business] off when you have to take a child to the sitter," says Mark, but they continue to juggle it all. They're managing it well, if their yearly sales of about $10 million to $20 million are any indication.

Everyday Harried Life

Finally, once you're well into the business, you'll find yourself dealing with all the little issues that come up daily, much like you do in your regular married life. And much like you promise to love, honor, cherish and forsake all others in your marriage, Miles suggests that married entrepreneurs do that in their businesses as well. "Are you willing to watch the other person's back?" asks Miles. Being loyal to your partner means you don't let employees pit one of you against the other--you must form a united front, she says. And that applies to vendors and clients as well. As much as you may be tempted to, don't treat others better than you treat your partner. Says Miles, "[Some entrepreneurs] honor their customers and clients ... but they growl at their partner."

Working from home can add another layer of complications when it comes to the everyday boundaries of business life and home life. Kim and Linda O'Neill, founders of both Lone Star PC Sound (www.pcsound.com), an online computer supply retailer, and The Supplies Room (www.the suppliesroom.com), an online office supply retailer, know those challenges well.