Using a mock injury involving arterial bleeding, we explored the impact of variables on two different decisions in the decision-making process leading to help. Expertise (Red Cross Training), ambiguity, and number of bystanders were manipulated in a 2 X 2 X 2 design. We observed the following responses: (a) nonhelp, (b) ineffective direct help, (c) indirect help, and (d) direct help. The decision to help or not was affected by ambiguity, sex, and the presence or absence of other bystanders. Greater ambiguity led to less help; women helped less than men; and fewer people helped when other bystanders were present. Expertise affected the decision leading to the type of help used but not the decision to help. Although training did not raise the intervention rate, it did dramatically change the effectiveness of the help used and could yield as many as 28 more saved lives out of 80 such incidents. The number of bystanders affected both the decision to help and the type of help used. Ineffective direct help occurred most frequently when the bystander was alone. The presence of other bystanders also affected the type of indirect help that was used.