The present study explores discourse and long-term effects of structured input and structured output when delivered in isolation or in combination on the acquisition of the English causative. Research investigating the effects of structured input has indicated that it is the causative variable in the positive effects of processing instruction. To provide answers to the questions formulated in this study, one classroom experiment was carried out. Sixty-eight school-age Greek learners (aged 10-12) participated. The participants were randomly assigned to three groups: structured input only group (n=22); structured output only group (n=22); combined structured input and structured output group (n=24). Subjects who scored lower than 50% in the pre-tests were included in the final data collection. Instruction lasted for three hours. The design included a delayed post-tests battery (immediate, three weeks after instruction, twenty-four weeks after instruction). The assessment tasks included an interpretation and production task at discourse-level. The results indicated that learners who received structured input both in isolation and in combination benefitted more than learners receiving structured output only. These two groups were able to retain instructional gains three weeks after instruction (short-term effects) in all assessment measures. Long-term effects after six months were also investigated.