This paper poses a modified Rogers (1995) model for the Innovation-Decision Process for designing in-service programmes for educational innovation. The proposal emerges from a study of eight in-service teachers struggling to implement an innovation - the process approach to teaching English writing in Hong Kong secondary schools over the course of a year. The findings appear to (1) substantiate the five stages described in the Rogers Model - Knowledge, Persuasion, Decision, Implementation and Confirmation - and (2) reveal complexities in an Implementation Stage when it is applied in the educational context which were not defined in the Rogers Model. The Implementation Stage is classified into four phases - Experiment, Adjustment, Mastery and Personalisation. Each phase is characterised by its own emerging phenomena and copying strategies. These findings provide a theoretical framework and principles for designing in-service programmes to address a process for change which would deepen teaching skills as will as the successful implementation of innovation.[Copyright of Evaluation & Research in Education is the property of Routledge. Full article may be available at the publisher's website: http://dx.doi.org/10.1080/09500799908666947]