This resource contains the R code and core results of a study seeking to identify whether there are global patterns in whether larger or smaller bodied species are showing different population trends within communities. This used the global BioTIME database (including community time series from hundreds of studies of mostly covering the last 20-50 years) and several large trait databases to gain a very large sample size (12,956 assemblage time series from 144 studies, incorporating 2,109,593 observations of 10,286 species, of which 7,234 could be linked to at least one size trait). Data resources in this deposit include matched trait values for each species, several population trends of each species, and community level correlations between population trends and body-size trait values. Additionally, html files describing the R markdown code to produce the data resources are included. This resource does not contain the raw population and trait data, which are openly available from various sources that are listed in the supporting documentation. The matching between global databases required a large amount of initial cleaning and filtering steps. Although the data was subject to a number of checks, with tens of thousands of species, it was too large to check all alignments manually, and trait matches assume a single bodysize value for a species across its range. The original purpose was to generate a relative rank within a community, but caution is needed for more fine-grained analyses using this approach. Full details about this application can be found at https://doi.org/10.5285/1f7687de-d68e-4349-b4d3-b7d3a127a7df