Abstract Supporting Information (SI) lets authors include material that aids specialists without being essential to a paper’s conclusions, or is not in a format suitable for an article (e.g., animations). In recent years, SI files at GRL have grown to dozens of pages, increasingly housing content that should be in the article itself. This editorial explains how the GRL editorial board now evaluates SI and why some submissions are returned without review as a result. The guiding principle is function, not quantity. A manuscript returned for excessive SI is typically a full‐length paper, not a letter, that is best served by reintegrating that material and submitting to a journal with a more generous length limit.