With the House health bill passed, Congress moves a step closer to making the biggest changes to the health system in more than four decades. Here's a look at what the bill would mean for various groups:

The uninsured: They're the biggest winners under the bill. Starting in 2013, it gives government subsidies to a chunk of low- and middle-income Americans and expands Medicaid to cover a greater swath of the poor. At the lowest income level, the subsidy would keep a family of four earning just over $29,000 a year from paying...