To sign up some of the estimated 100 million Americans who are not online, the Federal Communications Commission and private providers are trying to make broadband Internet access both less expensive and more valuable.

On Wednesday, the F.C.C. will announce commitments from most of the big cable companies in the United States to supply access for $9.99 a month to a subset of low-income households. The low introductory price is meant to appeal to new customers who have not had broadband in the past.

The F.C.C. is billing the initiative as the biggest effort ever to help close the digital divide. Because no federal funds are being invested, the initiative relies in large part on the cooperation of private companies. One such company, Comcast, started offering $9.99 monthly broadband service to some low-income households this year after promising the F.C.C. that it would do so when it acquired control of NBCUniversal.

By enlisting the cable companies as well as a wide range of nonprofit groups that will educate eligible families about the low-cost access, “we can make a real dent in the broadband adoption gap,” Julius Genachowski, the F.C.C. chairman, said in a telephone interview Tuesday.