This study examined the effects of early phonological training on emergent phonological and reading skills. Children (N = 364) were randomly assigned in small groups to a phonological training group (n = 117), or a control group (n = 247) including both a non-phonological training group and a non-trained control group. The phonological training began three years before the formal reading instruction starts in Sweden. It was carried out in two waves during six weeks at the age of 4, and during six weeks at the age of 5. All children, including the control children, received phonological training in kindergarten at the age of 6. Fluid intelligence (Gf) and phonological awareness at age 4 predicted phonological awareness at age 6 as well as reading related skills in grades 2 and 3. There were substantial main effects of the early phonological training on phonological skills and early reading skills. For all outcomes the training was, furthermore, most beneficial for children low on Gf, who are in the risk zone of developing reading difficulties.