The type A behavior pattern (TABP) was described in the 1950s by cardiologists Meyer Friedman and Ray Rosenman, who argued that TABP was an important risk factor for coronary heart disease. This theory was supported by positive findings from the Western Collaborative Group Study and the Framingham Study. We analyzed tobacco industry documents to show that the tobacco industry was a major funder of TABP research, with selected results used to counter concerns regarding tobacco and health. Our findings also help explain inconsistencies in the findings of epidemiological studies of TABP, in particular the phenomenon of initially promising results followed by negative findings. Our analysis suggests that these "decline effects" are partly explained by tobacco industry involvement in TABP research.