JERUSALEM — At least 250,000 Israelis took to the streets on Saturday night to demonstrate against the high cost of living and lack of affordable housing, the largest in three weeks of protests aimed at forcing social and economic issues onto the government’s agenda.

The popular protest movement, which crosses the traditional Israeli political lines of left and right, began with a Facebook call to pitch tents along a stylish Tel Aviv boulevard. A tent city sprang up, and smaller ones have mushroomed in parks all over Israel.

The young organizers, who struck a chord in a society that has long been quiescent on domestic issues, have expressed surprise at the number of Israelis who have joined their struggle.