The study investigated children's intention understanding using a longitudinal design. Thirty-two Italian children were tested on the 'Demonstration of Intention' in the Re-enactment paradigm devised by Meltzoff (1995a), at two ages. Mean age was 12 months at the first session and 15 months at the second session. Previous research by Meltzoff showed that 18-month-olds are able to re-enact what the adult intended to do, when an adult tried but failed to perform certain target acts. Bellagamba and Tomasello (1999) found that, compared to 18-month-olds, 12-month-olds are less able to imitate unsuccessful goal-directed actions. The current study had two main goals. The first was to replicate earlier findings on intention understanding in 12- and 15-month-olds longitudinally assessed. The second goal was to analyse which actions children perform when not producing the target act. A coding scheme was devised to evaluate these non-target actions. Results confirmed previous findings, i.e. children's tendency to produce the target act was higher at an older age. At a younger age the most frequent response was 'undifferentiated manipulation' of target objects, followed by 'approximation to the target action'. Since children differed in their intention understanding performance at the first session, we decided to check whether these individual differences remained stable at the second session. Individual children with high intention understanding performance at 12 months tended to remain high at 15 months of age.