Gather the ingredients.

Bring raspberries to a boil in a very large pot. Cook for 4 minutes. Add sugar and lemon juice; stir well. Bring back to a boil, stirring constantly. Cook for another 4 minutes.

Remove pot from heat and divide jam into sterilized jars, leaving 1/4-inch of space at the top. Wipe the rims of the jars with a moist paper towel to remove any food residue. Top with lids, and screw on rings.

Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil, then carefully lower the jars into the pot using a holder, leaving a 2-inch space between the jars. Pour in more boiling water if necessary until the water level is at least 1 inch above the tops of the jars. Bring the water to a full boil, cover the pot, and process for 10 minutes.

Remove the jars from the stockpot and let rest, several inches apart, for 8 hours. Store in a cool, dark area.