A portable tabletop assembly includes a horizontal tabletop, first and second pairs of legs for supporting the tabletop on a horizontal surface, a first crossbeam, and a height lock. Each pair of legs includes a first leg and a second leg pivotably connected to one another. Each leg has a first leg end, and a second leg end slidably coupled to the tabletop. The first crossbeam connects the first leg of the first pair of legs to the first leg of the second pair of legs. The height lock is engageable at infinite positions between raised and storage positions to inhibit horizontal sliding of the first crossbeam and the second leg ends of the first legs to fix a height of the tabletop above the horizontal surface. A method of adjusting the height of a portable tabletop assembly is also disclosed.