Back around Earth Day 1990, the Rainforest Alliance (RA) could only recruit one multinational company to work with. In those days, big business often viewed NGOs with suspicion.

Today, 20 Earth Days later, the group partners with four of the five largest tea companies in the world, along with major players in chocolate, coffee, home furnishings, office supplies and tourism, according to Executive Director Tensie Whelan.

"In 2010, collaboration with the Rainforest Alliance and other members of civil society is an asset," Whelan said, "not a liability."

Over the last several decades, the relationship between NGOs and companies has steadily evolved from conflict to cooperation. That's not to say the tension has completely dissipated -- it hasn't -- but businesses have realized they need NGO support for what has become a competitive issue. At the same time, NGOs understand that major change can't be achieved without the business community.

"What's changed fundamentally is that these aren't just defensive strategies," said Glenn Prickett, chief external affiars officer at the Nature Conservancy. "What the leading companies are doing is asking how can we do better as a business by embracing the environmental movement, being part of the solution."

Over the last 20 years, NGOs -- Environmental Defense Fund (EDF) and Nature Conservancy, in particular -- have heavily invested in understanding business and the operational options they have in terms of making business more sustainable, according to Aron Cramer, CEO and president of BSR.

"They have had to become more rigorous and more able to provide practical assistance to companies," Cramer said. "There has been a parallel development on the business side, where the knowledge and sophistication has also grown as they explore developing their capacity for learning how to derive real value from their sustainability investments."

Major corporations have had environmental advocates for years, but it's only been recently that they've been given their due, said Michael Kinsley, senior consultant with Rocky Mountain Institute (RMI).

"Twenty-seven years ago, most were marginalized in their companies," Kinsley said. "Now, they are in influential positions within corporations because they can provide strong business value and prove the economic case."

Early pioneers made the case for why NGOs and business partnerships could improve their environmental performance without increasing expenses. On its website, EDF points to its work with McDonald's in 1990 as the first collaboration between an environmental group and a leading corporation. EDF said it doesn't accept money from corporate partners, but others do.

EDF and McDonald's focused on cutting waste and conserving resources, eventually leading to McDonald's shifting to paper-based sandwich wrap packaging and incorporating significantly more recycled content in its paper products.

Additional companies and NGOs tested the waters. For example, Rainforest Alliance and it first multi-national partner, Chiquita, began working together in 1992, eventually certifiying all of the company's banana farms, in addition to 90 percent of its independent producers.

"This led to a complete transformation of their production practices, resulting in reforestation, improved working conditions, reduction of chemical use, increased yields, improved water quality, etc.," Whelan said in an email message.

It took years for these and other ideas espoused by environmental groups to become mainstream.

"What was regarded as heretical 25 years ago is now a given as far as many are concerned," said RMI's Kinsley. "The very idea that green solutions could be good for business and the economy didn't occur to many, and now an increasing number understand."

Cramer of BSR recalls the common inquiry he used to receive from businesses: Why do sustainability? Then they asked: How do you do it?

"Now they ask us, 'How do you do it and make it pay off?'" Cramer said. "It's less about changing attitudes then getting things accomplished. Partnerships have matured to help realize this vision."

Companies of all stripes have become more receptive to the benefits of reducing the environmental impacts, such as improved efficiency and brand-building, with the help of NGOs.

"We've always pursued these relationships so from our perspective nothing has changed," said Jeffrey Hollender, co-founder of Seventh Generation. "What has changed is that companies beyond the usual suspects have realized the value of these partnerships and so many more of them are forming."