Several dozen Walmart workers in Southern California staged a one-day strike on Thursday, according to workers and union officials, a move that culminated in a rally of some 250 workers and supporters in front of a Walmart store in Pico Rivera.


The strikers, who union officials said came from nine Walmarts in the Los Angeles area, said they were mainly protesting what they said was management’s frequent retaliation against employees who spoke up about working conditions.


Several of the workers, who said this was the first-ever strike against Walmart in the United States, also said they were protesting low wages and short hours.


Manuela Rosales, 25, who works in the cellphone department of the Pico Rivera store, said she walked out on Thursday, missing her afternoon shift, because “when we speak out, they cut my hours in retaliation and they have me pull pallets, which is very hard work.” She added, “I’m a single mom and I can’t afford them cutting my hours.”


Ms. Rosales said that about 30 of the 100 or so workers from her store’s morning shift walked out on Thursday.


Walmart, the nation’s largest retailer, sought to play down the job action, with a company spokesman saying it was a mere rally and not a real strike.


“You can count on less than one hand the number of associates that we are aware of who left their post to participate in the rally,” said Dan Fogleman, the Walmart spokesman. “That’s very few when you consider the more than 12,000 people that we employ in L.A. County.”


The rally outside the Pico Rivera store was boisterous, with workers carrying signs that read, “Stand up, live better,” and “On strike for the freedom to speak out.” The workers, who are not unionized, maintained that they were striking against unfair labor practices, specifically illegal retaliation, a claim that could protect them from being punished for walking out.


The walkout and rally were organized by Organization United for Respect at Walmart, or OUR Walmart, a group of several thousand Walmart workers that is closely affiliated with the United Food and Commercial Workers Union.


Dawn Le, a union spokeswoman, said 71 Walmart workers who were scheduled to work Thursday signed in to show participation in the strike and rally.


The rally attracted several prominent supporters, including Charles Calderon, majority leader of the California State Assembly; the Rev. Eric P. Lee, president of the Los Angeles chapter of the Southern Christian Leadership Conference; and María Elena Durazo, executive secretary-treasurer of the Los Angeles County Federation of Labor.


“Nobody is going to stop us from speaking out,” Ms. Durazo said. “Walmart may sell jeans and video games and all that, but the biggest product they sell in this country and this world is poverty.”


Mr. Fogleman said the rally was just the union’s “ latest publicity stunt.”


“Our stores in the community are staffed up and open for business,” he said. “This event is not a factor.”


Mr. Fogleman also denied that this was the first strike against Walmart in the United States, pointing to a 2006 protest by 100 workers at a store in Hialeah Gardens, Fla.


Thursday’s walkout occurred three weeks after several dozen employees at warehouses that serve Walmart walked off the job in California and Illinois to protest what they said were onerous conditions, including toiling in warehouses that they said sometimes heat up to 120 degrees. The California job action included a 50-mile, six-day march by warehouse workers from Ontario, Calif., to Los Angeles City Hall.


Mr. Fogleman said Walmart does not manage those warehouses but takes accusations of workplace problems very seriously. He said Walmart has sent people to those warehouses, and any legitimate problems have been addressed.