An undermount sink mounting system includes a support member adapted to engage a frame onto which a countertop is mounted. The support member upwardly supports a sink engagement lever, which is adapted to engage a sink in such a way that said sink engagement lever presses the sink upwardly toward the countertop when the sink is mounted. A height adjustment member is adapted to move the sink engagement lever upwardly to engage the sink and adjust how forcefully said sink engagement lever presses against the sink.