Matt Zambrano is discovering within himself an entrepreneurial streak he never learned as a boy. A third-generation Mexican American who grew up in Joliet, Ill., Zambrano has worked for 13 years weighing packages and selling stamps at the local post office--toiling in a world of job security and steady paychecks that conforms to his parents' ideal of success.

Slightly more than a year ago, he came across a book called "The Americano Dream," a kind of capitalist self-improvement manual written by Lionel Soso, a Latino marketing guru who counts among his clients several leading U.S. corporations and Republican presidential candidate George W. Bush. If Latinos are to prosper, Sosa argues in his book, they must shake off the passivity and other old-world religious values that inhibit financial ambition.

"I'm not a big book reader at all," Zambrano says, "but the moment I picked [it] up, I went from cover to cover."

Now, at 34, he has started a computer-based business in his spare time, selling pagers, long-distance telephone service and Internet access. He has taken a turn at marketing license plate holders for, an Internet service provider geared to Latinos. And in the last few weeks, he and a co-worker from the post office have begun trying to find financing for another start-up on the Web.

"I believe in the Anglo values: 'Show me the money,' " Zambrano says. "I'm not about 'The meek shall inherit the earth.' "

His newfound ambition, his risk-taking--so indelibly American--make Zambrano typical of fully assimilated Hispanics who have shed the fatalistic attitudes that are a hallmark of recent Latino immigrants. Yet he knows that his entrepreneurial zeal worries his parents, an accountant and a purchasing assistant for a U.S. Department of Energy laboratory who have not changed jobs for decades. It took him six months to persuade them to buy his telephone service. He suspects they did not want to encourage his less orthodox pursuits.

Such zeal is one of many traits that Zambrano says set him apart from his parents--and even further from his grandparents, who moved to the United States from Mexico early in the last century. His father's father came to Joliet to find work in a steel mill. His grandmother stayed home to raise their eight children. His mother's parents left home to become farm workers in Texas before migrating to Chicago, where his grandfather took a job in a Uniroyal factory.

As a boy, Zambrano watched his paternal grandfather carry out what struck him as a curiously old-fashioned custom: slaughtering pigs next to his suburban garage. His grandmother was forever patting tortillas and grinding peppers. They favored mariachi music.

And when his grandfather grew old, he handed down the silver coins he had saved. To Zambrano's parents and grandparents, the stock market "was thought to be for the Rockefellers and the Kennedys, not for the Zambranos and the Garcias," he says now.

Zambrano senses that his relationship to God is different too. His parents and grandparents have always believed in a stern God. "That old feeling of working by the sweat of your back. Kind of going with that God-fearing, 'What comes your way is your lot.' "

He and his wife, Marisa--who moved to Illinois from Guatemala as a girl--view God as loving, nurturing. "We feel [we should] use the talents God has given us."

"I grew up with many more Anglo values," says Zambrano, who took two years of Spanish in high school but does not really speak the language. "I guess that's the core of the difference between me and somebody who is just over the border."

Still, he has painfully intimate knowledge that America does not afford a good life to all Latinos of his generation. One first cousin in Chicago was murdered in a gang fight. Another was lured into a Hispanic gang, too, and was shot in the head. Still in his twenties, he is permanently confined to a wheelchair--his legs useless, his hands jerky, his speech slurred.

Zambrano's glimpses of violence, his awareness of Hispanic poverty, have only strengthened his resolve to forge a sheltered, prosperous life for himself, his wife and their two young daughters. And the more he strives for success, the more he is reaching out to motivate other Latinos--and the more he is connecting to his roots.

On a day off from the post office last October, he bought a $269 plane ticket and flew to San Antonio to meet Sosa, the marketing executive and self-made millionaire who had sparked his imagination. Over a 1 1/2-hour lunch in Sosa's office, his idol urged Zambrano to focus his energies like a laser. You must ask yourself, Sosa instructed him, exactly what you want to accomplish and when.

For weeks afterward, the question burned in his brain, nearly driving him crazy. Finally, one day, this immigrant's grandson realized he had the answer: "I, Matt Zambrano, want to be making $180,000 by 2003 by living the American dream."

CAPTION: Matt and Marisa Zambrano, with daughters Sophia, 3, and Jessica, 5, in their suburban Chicago home.