Infants were observed longitudinally at 14, 25 and 44 months of age in order to observe individual consistency and sex differences in a wide variety of tasks thought to measure temperament. Specific temperament variables were intensity of response (vigor), persistence, activity and toy play. In addition, the relationship between temperament and cognitive style (impulsive-reflective) was observed. The results indicate within age patterns in terms of temperament with greater vigor and activity related to less persistence and toy play. In general, there were no sex differences and little individual stability over the first three years of life. Finally, there was no indication that impulsivity reflex as measured by a Matching Familiar Figures task at 3 1/2 years, was in any way related to these temperament variables. (38pp.)