This study uses structural equation modelling to investigate the effect of primary school fourth-grade students' attitudes towards writing, writer's block and writing disposition on their writing success. Participants of the study included 735 primary school fourth-grade students. The results indicate that attitudes towards writing and writing disposition significantly and positively affect writing success that Wattitudes towards writing and writing disposition have a significant negative effect on writer's block and that writer's block has a significant negative effect on writing success. Another important result of the study is that attitudes towards writing and writing disposition play a mediating role in the effect of attitudes towards writing and writing disposition on writing success. According to path coefficients, the areas that have the largest effects on writing success can be identified as, respectively, writer's block, writing disposition and attitudes towards writing. The study results are then discussed in relation to the literature on the subject.