The effects of low-level environmental impurities, test temperature, sensitization heat treatment, and surface condition on crack initiation have been examined in Type 304 stainless steel in constant extension rate stress corrosion cracking tests. Tests were conducted at 288, 200 and 125°C in pure water environments containing 0.2, 0.2, and 1.8 ppm of dissolved oxygen, respectively. At 288°C in highly sensitized specimens, cracks initiated at less than 20% of life in pure water, with impurities accelerating initiation. The bulk pH affected initiation and failure strains, while increasing conductivity at neutral pH affected only strain to failure. At lower temperatures or lesser degrees of sensitization, crack initiation occurred later in life and impurity additions had a stronger impact. Shot-peening reduced the strain to initiation in constant extension rate tests, most noticeably at 125°C. The minimal data available for comparison support the findings of this study.