An experimental study of heat transfer into gas-fluidized beds has been carried out with heat transfer into discriminated areas of the boundary walls, and into single and multiple elements immersed in the bed. The experiments have been carried out with glass ballotini ranging in size from 100 mum to 1 mm in diameter, on Diakon (Perspex) particles of 325 mum, and on nickel particles of 275 mum and 325 mum covering a range of Archimedes numbers from 100 to 10(5). Beds of different diameter with distributors of several different types have been examined. The entire experimental results have been compared with literature data on heat transfer to immersed elements. It is shown that the onset of slugging in the fluidized bed has a large effect on heat transfer. Once the effect of slugging has been introduced, it is shown that the results of this investigation and others in the literature within the range of Archimedes numbers from 100 to 10(9) may be correlated.