A gas scintillation counter is described which operates to 40 atm pressure. An attempt was made to maximize the scintillation light output in helium. Helium scintillation properties studied with this counter include the effect of various wall-coating materials, gas-purity effects, the linearity of pulse height with energy, and the variation of pulse height with pressure. With purified helium and for a given amount of energy deposited in the gas, the scintillation pulse height was found to increase with pressure P approximately according to the function kP/(1+KP), where k and K are proportionality constants. A semiquantitative argument is presented, explaining this pulse-height increase with pressure in terms of electron-ion recombination times in helium.