The purpose of this study is extend previous methods by Raudenbush and Liu (2001) and Spybrook et al. (2011), and provide methods for power analysis of tests of treatment effects in studies of polynomial change with two levels of nesting (e.g., students and schools) where the treatment is either at the third level (e.g., school intervention) or at the second level (e.g., student intervention). In particular, the authors provide methods for power analysis for block randomized designs (BRD) where the treatment is at the second level (e.g., student intervention) and the third level units (e.g., schools) serve as blocks. Please note that methods for power analysis for cluster randomized designs (CRD), where for instance schools are randomly assigned in a treatment and a control group, is omitted in this proposal because of words limits. Figures are appended.