When you buy a co-op apartment, you become a shareholder in a corporation, and you have a responsibility to it ensure that it thrives.

Q: Two years ago, I bought an apartment in a 10-unit, East Village co-op. The co-op board and management are a mess. Our managing agent just told us they would not renew the building’s contract when it expires, and the board president, who owns three units with rent-stabilized tenants, announced he is quitting. None of the remaining seven owners (including me) is willing to take on the role. What will happen?

A: A co-op needs someone to run it. That job usually goes to a managing agent who collects maintenance from shareholders to pay critical bills like taxes, insurance, the mortgage, and heat and hot water. A property manager also negotiates contracts and supervises staff so that the halls get cleaned and the garbage gets taken out. Smaller buildings sometimes operate independently, without management, by delegating tasks to shareholders, but the work still needs to get done. Otherwise, at the most basic level, the building will not function.

When you bought your apartment, you became a shareholder of a corporation. You now have a responsibility to it ensure that it thrives.

What happens if a pedestrian slips on an icy sidewalk in front of the building? Or if the heat gets shut off or a burst pipe does not get repaired? The rent-stabilized tenants and shareholders could withhold rent or maintenance, or even sue the co-op. Fines could be levied. As the building deteriorates, you could lose your investment in your apartment, and may not be able to sell it.

“You are a shareholder in a very small corporation. You guys are very close to the edge,” said Beatrice Lesser, a real estate lawyer and a partner at the Manhattan law firm Gallet Dreyer and Berkey. “Not everybody is cut out for these responsibilities. These people should either be renters or buy into a bigger building.”

If no one wants to join the board, shareholders could hire someone to be an officer of the co-op, depending on the bylaws, Ms. Lesser said. That person could either serve as managing agent or find someone to take the job. However, small buildings often have trouble finding property managers, so shareholders may have to get involved.

Taking on a leadership role may feel overwhelming, especially when the building is in disarray. However, New Yorkers with no prior experience join co-op boards and run them well. Educate yourself. Seek advice from board members of successful small co-ops. Explore resources like the New York Cooperator and Habitat Magazine. There is an upside to stepping up: You get to make critical decisions about your investment, your building and your home.