Companies have always depended on suppliers to keep their operations running smoothly and efficiently. But these days, those relationships are more critical — and more complicated — than ever.

With global competition heating up, technology accelerating at unprecedented levels and customers growing more demanding, companies must deliver new products and services faster — and many businesses are finding they can’t keep pace. So they’re increasingly collaborating with their suppliers to design new marketplace offerings and improve their processes.

Cellphone companies, for instance, must constantly churn out new models to keep up with the rapidly evolving industry. But they don’t have the resources or expertise to design all of the new components in-house, so they often turn to suppliers to design parts such as batteries, antennas and casings. Virgin Mobile, one of the fastest-growing cellphone-service providers in the U.S., has outsourced all of the technical aspects of the business, everything from cellphone design to network infrastructure.

The problem: As these collaborations grow more important, the failure rates are significant. Products often end up reaching the market too late to beat the competition or to make the crucial holiday season, or they come in way over budget.

We wanted to figure out what makes collaborations fail — and succeed. After numerous field interviews, focus groups and a survey of more than 450 supply-chain professionals, we discovered four crucial factors that separate companies that do well in collaborations from those that don’t. Companies that excel in these areas achieve strikingly better results — not just with the job at hand but also in building a strong long-term relationship with their partners.

What follows is a close look at those factors and how companies can improve their ability to handle collaborations.

But, first, we need to answer