Many companies take a very holistic, work-plan-centric view of integration. That approach is understandable-everyone wants to tackle problems in a comprehensive way-but it contains a major pitfall. The truth is, only a few integration activities really drive the success of a deal. If taking a broad-based approach makes acquirers take their eye off those few key activities, it can be a recipe for trouble.

While every integration-like every merger-is different, a number of guiding principles apply across almost all integration efforts. They all revolve around a central question: Where do operations really need to be integrated, and where can the merging businesses simply carry on separately? The answer lies in a set of four decision principles:

Plan for ownership. Ideally, acquirers should launch their integration planning months before the deal is publicly announced. Many of the toughest integration decisions will be about people. Management should link all decisions tightly to the deal's investment thesis and to the synergies and cultural issues identified during due diligence.

Integrate quickly in critical areas. Carefully target areas for integration based on the deal's investment thesis. Mergers