imits children's text production. This interpretation would
also be consistent with the difficulties experienced by children with
language impairment in monitoring and editing their written productions
(Scott, !999). As long as translating continues to place heavy cognitive
demands on writing, management of planning will be impaired.
In our second model we explored the longitudinal predictors for the
participants' writing performance at age 16. This model identified
direct effects of reading, spelling, and writing at age 14 on writing at
age 16. These data demonstrate the ways in which both phonological and
morphological literacy measures come to the fore in the writing
performance for these students. As in the regression models,
nonphonological factors were also evident and, unlike the literacy
measures, their impact was traced back to age 8. Vocabulary appears to
provide an indication of the semantic knowledge which supports both
writing at age 11 and sentence formulation at age 14. Over time, both
reading and writing skills mediate the impact of oral language.
The concurrent and the longitudinal models both provide evidence to
support specific student-based factors that impinge on the production of
written text, and offer scope for targeted and strategic interventions
(Troia, 2006) and interventions which could compensate for text
production difficulties (MacArthur, in press). It is unlikely that these
factors alone explain the relative decline in writing performance. As
the change scores demonstrate, only writing fluency predicted
change--and this factor accounted for 29% of the variance. An important
question remains about the support in writing that is provided once
students enter secondary school, both to maintain current levels of text
production and to enhance their capacity to produce texts closer to
expected targets. Support for those who struggle at this phase of
education in England is "uneven" (Office for Standards in
Education, Ofsted, 2007, [paragraph] 75, page 31), and differentiation
of the curriculum often involves simplifying activities (Dockrell &
Lindsay, 2007). Government initiatives to improve skills at this stage
have not been successful, with less able children being left behind and
catch-up classes for those who struggled in primary school failing to
bring students up to the expected standard (Ofsted). Typically these
interventions focus on word reading and are provided for most students
aged 12 to 14. Thus, given evidence from both the school reports for
these students (Dockrell, Lindsay, Palikara, et al., 2007) and the
current educational context, it is unlikely that students with SLI are
receiving the support they require to develop their writing skills. A
lack of appropriate interventions and support resources further
disadvantages these struggling writers. This lack of support has been
highlighted in other educational systems (see Moni et al., 2007; Troia
& Maddox, 2004).
Investigations of written language are complex and subject to a
number of limitations. The current study is limited by the small sample,
the use of a single writing measure, and the lack of information on the
children's wider information processing skills. Given the purported
importance of vocabulary a more detailed examination of the
students' competence in this area is needed. It is not clear the
extent to which the vocabulary measure is tapping the breadth of the
children's knowledge, the depth of their semantic representations,
or the efficiency of lexical retrieval. There is increasing evidence
that measures of depth and breadth of vocabulary may have differential
effects on reading, and we expect similar patterns to be evident in
writing (see, e.g., Ouellette, 2006; Tannenbaum et al., 2006). Future
work should pay specific attention to the nature of the evidence for
interventions provided to support writing, including the skills that
underpin performance in writing and the strategies provided for
coordination of these skills.
Care also needs to be taken in generalizing performance on our
writing task. The decline in