This volume in the well-established Methods in Enzymology series features methods for the study of lipids using mass spectrometry techniques. Articles in this volume cover topics such as Phospholipase A1 assays using a radio-labeled substrate and mass spectrometry; Real-time Cell Assays of Phospholipases A2 Using Fluorogenic Phospholipids; Analysis and Pharmacological Targeting of Phospholipase C a interactions with G proteins; Biochemical Analysis of Phospholipase D.; Measurement of Autotaxin/Lysophospholipase D Activity; Platelet-Activating Factor; Quantitative measurement of PtdIns(3,4,5)P3; Measuring Phosphorylated Akt And Other Phosphoinositide 3-Kinase-Regulated Phosphoproteins In Primary Lymphocytes; Regulation of Phosphatidylinositol 4-Phosphate 5-Kinase activity by partner proteins; Biochemical Analysis of Inositol Phosphate Kinases; Analysis of the phosphoinositides and their aqueous metabolites; Combination of C17-sphingoid base homologues and mass spectrometry analysis as a new approach to study sphingolipid metabolism; Measurement of mammalian sphingosine-1-phosphate phosphohydrolase activity in vitro and in vivo; A rapid and sensitive method to measure secretion of sphingosine-1-phosphate; Ceramide Kinase and Ceramide-1-Phosphate; Measurement of Mammalian Diacylglycerol Kinase Activity in vitro and in Cells; Lipid Phosphate Phosphatases from Saccharomyces cerevisiae.