Embodiments of a method and/or system for characterizing an allergy-related condition for a user can include one or more of: generating a microbiome dataset for each of an aggregate set of biological samples associated with a population of subjects, based on sample processing of the biological samples; processing a supplementary dataset associated with one or more allergy-related conditions for the set of users; and performing an allergy-related characterization process for the one or more allergy-related conditions, based on the supplementary dataset and/or microbiome features extracted from the microbiome dataset.