This document provides guidance for conducting a comparability exercise between a proposed biological product (BP) and an authorized comparator biological product (CBP) for the purpose of biological product registration. It outlines the quality, stability, manufacturing process, and data requirements that must be evaluated and presented in a comparability study to demonstrate that the BP is similar to the CBP, upon which reduced nonclinical and clinical data can be relied. Key aspects that must be compared include quality attributes, samples from manufacturing process stages, stability under stress conditions, and data from multiple batches. Significant unjustified differences found would indicate the products are not similar.