The Federal Reserve, increasingly optimistic about the economy, is dialing back its stimulus efforts. The International Monetary Fund has raised its forecast for growth in the United States. Congress has long since reduced aid to the economy, with many lawmakers, mostly Republicans, adamant that the economy is better off with less government involvement.

The official line is clear: The worst is over, and recovery has given way to expansion.

But that’s not the whole story. Economic gains so far have mostly benefited those at the top of the income and wealth ladder. Worse, future growth is likely to be lopsided, because the foundation for broad prosperity is arguably the weakest it has been since World War II.

Take, for example, Americans age 25 to 34, the leading edge of the so-called millennials, the generation born in the 1980s and 1990s. They are worse off than Gen Xers (born from the mid-1960s to the late-1970s) were at that age and the baby boomers before them by nearly every economic measure — employment, income, student loan indebtedness, mobility, homeownership and other hallmarks of “household formation,” like moving out on their own, getting married and having children.

This group had the bad luck of entering the work force in the depressed and slow-growth years that started when the recession hit in 2007. Instead of spending the crucial early years of their work lives laying the groundwork for a solid economic future, many of them have struggled with unemployment and underemployment, and many have fallen so far behind where they would hope to be that recovering lost ground may well be impossible.