(FORTUNE Magazine) – IT WAS ON a Wednesday night last June, at one of our quarterly executive councils, when [GE's CEO] Jeff Immelt pulled me aside and said, "I'm thinking about restructuring the businesses, and there's an opportunity for you to run Plastics." He told me that he would promote me to senior vice president whether I stayed running GE Rail or I moved. "It's up to you," he said. This was a first. I've had nine different jobs since I joined GE in 1988, and usually I'm told, "We want you to do this."

I was happy at GE Rail, where we manufacture locomotives. I started running the business at the end of 2002 when it had revenues of $2.3 billion. We grew it to $3.5 billion. I thought, I'm in a good place. I love the business. Plastics is double the size, $7 billion in revenues, so it would be a step up. But I didn't know much about plastics. I did know that profits were down 40% in four years, and that sales were flat. And because the raw material in plastics is a derivative of natural gas, costs are going up like crazy. My stress would go up tenfold. I would have to move my family again--and my 11-year-old daughter had moved six times already. My husband, Chris, would have to find a new teaching job in Pittsfield, Mass. Everything would be tougher.

I talked with Dave Calhoun, who was my boss. He wanted me to stay at Rail because we were making great progress. Susan Peters, our head of executive development, encouraged me to move. She said, "You're going to get a much broader perspective in Plastics. And you'll make decisions that have a bigger and more immediate impact on the business." I flew home to Erie [Pa.] the next day, and that night, Chris and I sat with two glasses of wine and a pad of paper, making lists and talking for more than three hours. We decided that this is a big risk, but even if I fail, I'm going to learn a ton. The next morning I called Jeff and told him I'd do it.

When Chris and I told our three daughters, my oldest looked at me and said, "I don't want to move. I'm tired of making new friends." She locked herself in her bedroom. She was miserable for two days. But since we moved, two days before school started, they all say they like their new home. It's turned out to be our smoothest move yet.

The Plastics job is more exciting than I could have imagined. It's a technology hotbed, and the fast pace of the business is a great match for my personality and management style. I really enjoy that on any given day a decision requires our leadership team to take into account both the complex industries we serve and the impact of global events. There are very high stakes involved, but it's tremendously rewarding.