The aim of this work is to understand the nature of anion disordering in pyrochlore oxides and to establish what, if any, correlations exist between the anion position, disorder and cation disorder. This will be achieved through care examination of both the composition and temperature dependence of the structures of a number of Zr doped Y2Ti2O7 samples.Lanthanoid pyrochlores, Ln2M2O7, (Ln = lanthanoid, M = Ti, Zr) are being actively developed for use in solid oxide fuel cells, thermal barrier coatings, and for the storage of nuclear waste. Their suitability for these applications is thought to be a consequence of their flexibility with respect to anion disorder.