Experiments on pool boiling heat transfer in saturated R-113 at 1 atm pressure are conducted to investigate anomalies associated with the initiation of boiling using horizontal, 0.13 mm diameter chromel wires and a 0.51 mm diameter, platinum thin-film heater. Wall incipience superheat values of up to 73°C and wide variations in incipience superheats (more than 20°C) from case to case for nominally identical cases are observed. Presentation of incipience superheat results in terms of probability distributions is therefore recommended. The significant influence of the minimum heat flux and corresponding minimum wall superheat (after the cool-down portion of one run and the beginning of the subsequent run) on the incipience superheat excursion is observed. Tests with large step changes in heat flux, using a thin-film. cylindrical heater, indicated increases in incipience superheat of as much as 20% over tests with a series of incremental steps in heat flux up to the same heat flux level.