Lipid phosphate phosphatases (LPPs) are a family of integral membrane glycoproteins that catalyze the dephosphorylation of a number of bioactive lipid mediators including lysophosphatidic acid (LPA), sphingosine 1-phosphate (S1P) and phosphatidic acid (PA). These mediators exert complex effects on cell function through both actions at cell surface receptors and on intracellular targets. The LPP-catalyzed dephosphorylation of these substrates can both terminate their signaling actions and itself generate further molecules with biological activity. Recent advances have revealed that a family of structurally related genes is responsible for LPP activities in species from yeast to mammals. These genes exhibit distinct but overlapping expression patterns and their products appear to be heterogeneous with respect to their posttranslational modification and subcellular localizations. Here we review the structure and catalytic properties of the LPPs and consider recent developments in understanding their cellular biology and functions.