In this article, the author presents the results of a state project that focused on the effect of developing informal written computation processes through Years 2-4. The "developing computation" project was conducted in Tasmania over the two years 2002-2003 and involved nine schools: five government schools, two Catholic schools, and two independent schools. All Years 2, 3 and 4 teachers (a total of 37 teachers) in the project schools were involved. All teachers in the project agreed that the concentration on mental computation had greatly increased children's competence and confidence in handling numbers and in understanding place value. Most schools saw prep or kindergarten as the best time to start this approach for the majority of children. Whereas most teachers previously would have advocated the introduction of standard written algorithms from Years 1 or 2, they now suggested Year 4 as more appropriate. All teachers agreed on the benefits of developing informal written methods as a bridge between mental and formal written methods. (Contains 1 table and 4 figures.)