Americans' wealth hit a fresh record in the first quarter amid a rise in home values and stock prices, a trajectory poised to continue as U.S. markets push higher but one that doesn't necessarily figure to rev up the sluggish recovery.

The net worth of U.S. households and nonprofit organizations—the value of homes, stocks and other assets minus debts and other liabilities—rose roughly 2%, or about $1.5 trillion, between January and March to $81.8 trillion, the highest on record, according to a report by the Federal Reserve...