Image credit: OurWalmart/Facebook

Evelin Cruz used to be terrified of to speak up at work. A department manager at Walmart in Pico Rivera, Calif., for the past eight and a half years, Cruz, 41, feared she would lose her job if she spoke up against perceived injustices.

"People were really tired that any time they would speak out against the pay, hours, how much they would work, that management would cut their hours or not give them a schedule," said Cruz, who is one of thousands of members of Our Walmart, a labor organization backed by the United Food and Commercial Workers that defends Walmart workers' rights, told ABC News. "The retaliation was just enough."

On Thursday, about 30 employees from the Pico Rivera store, including Cruz, wielded signs that read "Stand Up, Live Better, Stop Retaliation" and "Stop Trying to Silence Us" and marched outside the store. At the same time, workers at eight other Walmart stores in California also protested working conditions and treatment.

It was the first-ever employee walk-out in the company's 50 year history, said Dawn Le, a spokeswoman for Making Change at Walmart, a coalition whose mission is to change the way Walmart conducts business.

"Everyone else has a union," said Le. "Workers in every other country - Japan, the U.K., Nicaragua, South Africa, Brazil, Argentina - have been able to form a union, except the U.S. and Canada. We just don't understand the double standard Walmart has. How come those in other countries get to have a voice, yet not in the U.S., its home country?"

Walmart spokesman Dan Fogleman disputed Le's charges, claiming that most employees have "repeatedly rejected unionization. "They seem to recognize that Walmart has some of the best jobs in the retail industry - good pay, affordable benefits and the chance for advancement," he said in a telephone interview with ABC News.

Walmart and its practices have made the news a lot lately. In mid-September, warehouse workers in Southern California were on a 15-day strike that included a six-day, 50-mile pilgrimage for safe jobs. Around the same time, hundreds of people marched in Dallas and San Diego, demanding better work conditions.

On Monday, Chicago police dressed in riot gear arrested 17 peaceful protesters blocking the entrance to a warehouse operated by an outside contractor that supplies Walmart stores, in Elwood, Ill. The protestors were there to show support for workers who had been on strike since Sept. 15, the Chicago Sun Times reported. What's more, the company faces yet another sex discrimination lawsuit, filed on behalf of 100,000 women in California and Tennessee.

According to Dan Schlademan, director of Making Change at Walmart, Walmart employees across the U.S. have recently filed more than 20 charges of unfair labor practices with the National Labor Relations Board. "Workers find how Walmart has tried to retaliate by cutting their hours and not scheduling them for certain shifts when they tried to speak out, and they're tired of it," he said.

But the $16 billion dollar company sees it differently, arguing that the California rally was simply a "publicity stunt by the UFCW to seek media attention in order to further their political agenda and financial objectives," said Fogleman.

Cruz, who makes $13.20 an hour - up from $7.40 when she started - begs to differ. "We just wanted to be treated like humans, not robots. We do have health insurance, but in most cases, you're not even making enough to live on, let alone take anyone to the hospital."

And though she worries about losing her job, she didn't see another option but to voice her anger. "We are still worried that they might retaliate," said Cruz. "We know exactly how they operate. They wait until you feel confident, or put down your guard, and then they come after you one way or another. But that's how tired we are of what's going on in the stores."