TheWorkshoponRandomizationandApproximationTechniquesinComputer Science, Random 98, focuses on algorithmic and complexity aspects arising inthedevelopmentofe cientrandomizedsolutionstocomputationallydi cult problems. Itaims, inparticular, atfosteringthecooperationamongpractitioners andtheoreticiansandamongalgorithmicandcomplexityresearchersinthe eld. RANDOM 98, heldattheUniversityofBarcelona(UPC), October8{10,1998, isthesecondintheseries, afterBologna. This volume contains all contributed papers accepted for presentation at theworkshop, togetherwithinvitedlecturesbyJosepD az(UPCBarcelona),...