Sammy Sosa sat in front of his locker before a recent game at Wrigley Field talking about his new sideline as a philanthropist. It all began when a real estate development project in his hometown in the Dominican Republic went down the tubes.

Speaking in Spanish, Slammin’ Sammy lamented his inversion fuerte in the construction of a three-story mall and office complex he’d hoped would become a bustling commercial center. It was indeed a “strong investment”—$3.5 million. Named the 30/30 Plaza after Sosa’s 30 home-run and 30 stolen-base seasons in 1993 and 1995, the complex had created construction jobs but no sustained economic growth.

The reality is that the mall is located in an impoverished country. Sosa’s hometown, San Pedro de Macoris, is famous for rearing residents with an extraordinary knack for baseball—scores of native sons played in the minors this season and at least a dozen are in the big leagues, including Toronto Blue Jays third baseman Tony Fernandez and Cubs shortstop Manny Alexander. But these success stories largely grow out of a desperate lack of alternatives. The local economic base includes a half-dozen crumbling sugar mills and a custom-free zone for industrialists taking advantage of cheap labor.

Two years ago, while watching the Florida Marlins win the World Series on television at a friend’s condo in suburban Miami, Sosa met Mexican-American attorney Art Sandoval. He mentioned his troubles managing the building in San Pedro de Macoris. And at the ballplayers’ request, Sandoval visited the city; he saw there weren’t many businesses that could afford the $250 monthly rent. “There wasn’t a market for the plaza,” Sosa says.

Sandoval proposed a solution: start a philanthropic foundation. By that time Sosa was already giving away $500,000 a year to needy family and friends. “I’m a person who knows where I came from,” he says. “In my country, there’s a lot of crisis, little work. The situation is hard. I’ve been able to establish myself in the major leagues. I’ve had the ability to help people by giving away a lot of gifts.”

Sosa said he would run Sandoval’s idea by his confidant Bill Chase. Sosa had known the New England-born businessman since he was a boy. Sosa’s father, a mechanic on a sugar plantation, had died in the mid-70s, and Sammy and his brother Jose were forced to hustle on the street for coins to help their mother put food on the table. Chase, who had come to San Pedro de Macoris to start a shoe factory, often stopped on his evening strolls to get a shoeshine from the Sosa brothers. Eventually he put them to work doing odd jobs around the factory. By the mid-80s, Chase had three factories in the country employing 1,500 people and manufacturing $60 million in shoes a year. He’s included the Sosa family in his will. After selling the shoe business and retiring to Florida in 1994, Chase watched with pride as Sosa became a bona fide major league star. But despite multimillion-dollar contracts, Sosa hadn’t shaken his childhood mind-set: he never planned much further than his next meal. Chase says, “I was worried that Sammy might wake up one day after his playing days are over and discover that he was back where he’d started.” The misguided mall only served to fuel these fears.

When Chase met with Sandoval, the lawyer explained that with a foundation Sosa could help his countrymen and at the same time shelter his wealth from the Internal Revenue Service. “Bill realized this made tax sense,” says Sandoval. “Even though he and Sammy didn’t know me, he could audit everything. Today Bill is the foundation’s director of administration. He signs all the checks. And I direct the operations.”

The 30/30 Plaza became the first asset of the Sammy Sosa Foundation. They considered turning the building into a hospital, but this idea was eventually deemed too costly. Preventive medicine was a different story. Widespread availability of tetanus shots alone could work wonders. Foundation officials worked with the Dominican Republic’s health department, the U.S. Agency for International Development, and the Centers for Disease Control to devise a program to provide free immunizations against measles, mumps, diphtheria, and tetanus to the children of San Pedro de Macoris.

Then last summer, as Sosa and Mark McGwire’s home-run derby captivated the world, Hurricane Georges swept through the Caribbean islands. In the Dominican Republic several hundred people were killed and 100,000 were left homeless. A stunned Sosa gracefully turned his daily media sessions into a publicity machine to illuminate the plight of his homeland. Buoyed by a half million dollars in donations from Sammy’s fans in the U.S., the foundation arranged the delivery of 80,000 pounds of emergency foodstuffs and 25,000 pounds of medicine. The foundation has also shipped donated food and clothing.

Checks for hurricane relief are still arriving at Wrigley Field, but these are being returned. “We insert a note explaining the purpose of the Sosa Foundation,” Cubs community relations director Rebecca Polihronis says. “Many people send the checks back.” Sosa routes his donations through the foundation too. “I used to give a lot of gifts to people, but now it all goes through the foundation.”

This past Tuesday Sosa’s preventive-medicine clinic finally opened its doors in his 30/30 Plaza. The program plans to vaccinate 100,000 children over the next year. The complex will also house a lab, a pharmacy, and social-service agencies. Foundation officials would like to establish similar clinics throughout the Dominican Republic and hope to attract volunteer medical personnel from the U.S. and elsewhere.

On Thursday, September 2, from 11 AM to 7 PM, the foundation will hold a fund-raiser hosted by the Cubby Bear, 1059 W. Addison. For one dollar you’ll get a hot dog—compliments of the Wisconsin-based Hebrew National Co.—and a raffle ticket. Prizes include Sosa-autographed memorabilia and four tickets to the Cubs opener next season.

The Sammy Sosa Foundation far exceeds IRS requirements that a philanthropy must give away 5 percent of its endowment each year to retain its tax-exempt status. “We give away about 85 percent of our assets,” says Sandoval. “The needs are so great that we spend money as fast as it comes in. If we can raise $6,000 at the Cubby Bear, that’ll buy the vaccinations for 1,000 children in Sammy’s hometown.”

To make a tax-deductible contribution to the clinic, send checks to the Sammy Sosa Foundation, 17901 NW Fifth Street, Suite 201, Pembroke Pines, FL 33029, or call 954-442-8810.