Tens of thousands of jobs in Berkshire rely on UK trading links with the European Union.
The europe4prosperity campaign has kicked off and will outline how UK's membership of the EU is vital to employment across South East England.
Catherine Bearder, an MEP for the South East, spoke to business leaders at CBI Thames Valley before joining fellow Liberal Democrat activists in Forbury Gardens, Reading, on Friday to launch the campaign.
She said: "It is important people understand the impact of potentially leaving the European Union would be felt in every city, town and village.
"So many of our businesses have benefitted from an ability to trade freely with other member states.
"Right now in Berkshire, more than 50,000 jobs rely on a stronger relationship with the EU, with the UK key to decisions affecting our economy.
"Our membership of the EU is a local benefit to all of us. That is not something we should be putting at risk."
Catherine chose to start the www.europe4prosperity.com campaign in Reading at the heart of her South East constituency.
The area is also home to a host of multi-national companies, a focus for EU investment and a draw for European students.
Catherine added: "Reading University has benefitted from a host of EU grants, while money has been used for big infrastructure projects.
"This is exactly the kind of opportunity which provides work for hundreds of people. I believe in working to improve the European Union to help protect and create jobs in places like Reading."