YCo0.88Ga3Ge has an incommensurately modulated structure that was solved with (3 + 1)D superspace techniques. YCo0.88Ga3Ge crystallizes in the orthorhombic superspace group Immm(alpha 00)00s with unit cell constants of a = 4.1639(4), b = 4.1639(4), c = 23.541(2) angstrom and a modulation vector of q = 0.3200(4)a* at 293 K. The incommensurate modulation, which creates a very large supercell (similar to 25 fold), arises from a charge density wave (CDW) in the square net of Ga atoms that is coupled with a site occupancy wave (SOW) of Co atoms. The distorted Ga net features polygallide ribbons, chains, as well as single atoms. Temperature dependent crystallographic studies of the structure from 100-500 K indicate that the CDW is "locked in". Electrical conductivity and thermopower measurements in the temperature range of 300-500 K show that YCo0.88Ga3Ge is a poor metal.