This chapter will review the different methods of measuring lung nodules, how these measurements are incorporated into malignancy risk assessment and management, and management strategies for pulmonary nodules, whether discovered incidentally or as part of lung cancer screening. Both manual and automated methods for measuring nodule size will be described. The advantages of automated methods, such as greater reproducibility and the ability to calculate volume doubling time, will be discussed, as will their limitations. The differences between solid and subsolid nodules will be presented, with particular emphasis on the differentiation between pure and partially ground glass nodules and the impact of this differentiation on size measurement. Density measurements and morphological criteria suggesting benignity or malignancy will also be reviewed.