Preheat oven to 350 degrees. For crust, combine graham cracker crumbs, butter and ⅓ cup sugar. Press mixture into bottom and up sides of a 9-inch deep-dish pie plate.
Bake until golden brown, about 10 minutes. Let cool completely.
For filling, whisk egg yolks with condensed milk until blended and then add lemon juice and stir until combined. Pour this mixture into the graham cracker crust.
For meringue, beat the egg whites with an electric mixer on medium speed until soft peaks form. Add ⅓ cup sugar, 1 tablespoon at a time, while beating on high speed. Continue beating on high speed until the sugar dissolves and stiff, glossy peaks form.
Spread the meringue over top of lemon mixture, making sure the meringue seals the edge of the pastry. Bake for an additional 10 minutes, or until meringue is golden brown.