This paper aims at reconsidering some analytical measures to best encapsulate the interlanguage, in writing, of young beginner learners of English as a foreign language in the light of previous and work-in-progress research conducted within the BAF project, and in particular, whether clause and sentence length should be best viewed as a fluency or syntactic complexity measusre or as part of a different construct. In the light of a factor analysis (Navés, forthcoming) and multivariate and correlation studies (Navés et al. 2003, Navés, 2006, Torres et al. 2006) it becomes clear that the relationship between different analytical measures is also dependent on learner¿s cognitive maturity (age) and proficiency (amount of instruction). Finally, clause and sentence length should not be viewed as either a fluency or sytactic complexity measure but as part of a different construct. It is concluded that further research using regression analysis and cluster analysis is neeed in order to identify and validate the constructs of the writing components and their measurements.