Definitions and codes for identifying vegetation seral status and structure are desired for land management planning, appraising wildlife habitat, and prescribing vegetation treatment. Codes are only presented; they are not a system for determining seral status or stand structure. Terms defined are climax, potential natural community (PNC), succession, seral status, thresholds, altered PNSs, life-form layer, dominant species, successional indicator species, structure classes, cover, and strata. Plant communities may be divided into three life-form layers where appropriate: tree, shrub, and herb/cryptogam. Each layer may be appraised and coded separately for seral status, or a single code may be used. Coding is provided for plant community structure class according to size, cover, and strata in a life-form layer. Seral status and structure may be coded together.