Put graham crackers in a large reseable plastic bag, and crush them with a rolling pin until very fine crumbs form.
Pour crumbs into a medium bowl; stir in sugar add butter, and stir until well combined.
Press crumb mixture into a 9-inch springform pan; spreading it 1 1/2 to 2 inches up the side; press flat. Chill crust in freezer at least 10 minutes.
Meanwhile, make the filling. Using an electric mixer set at medium high speed, beat cream cheese in large bowl until smooth. Beat in the condensed milk a little at a time. Beat in lemon juice and vanilla.
Pour filling into crust, cover and refrigerate 2 1/2 to 3 hours.