This paper reports on research designed to test a dynamic model of the causes of organizational innovation. Two communication variables (level of information and group communication) and three motivational variables (perceptions of equity, expectations of benefits, and perceived social pressure) were derived from equity theory, expectancy theory and the theory of reasoned action. These variables were used to predict the number of innovative ideas contributed by members of the organizations. Weekly data were collected for over a year from five firms and were analyzed with multivariate time series techniques. The results indicated that the communication variables were causes of organizational innovation but the motivational variables were not. Across the five firms, the variance explained by the model ranged from a low of 30 percent to a high of 78 percent. In four of the five firms, the forecast accuracy for the amount of individual innovation ranged from a low of 77 percent to a high of 85 percent.