To compare and summarize the mechanisms, frequencies of occurrence, and classification schemes of spontaneous, experimental, and genetically engineered mouse skeletal neoplasms, the literature was reviewed, and archived case material at The Jackson Laboratory was examined. The frequency of occurrence of spontaneous bone neoplasms was less than 1% for most strains, with the exceptions of osteomas in CF-1 (5.5% and 10% in two studies) and OF-1 outbred strains (35%), and osteosarcomas in NOD/ShiLtJ (11.5%) and NOD-derived (7.1%) mice. The frequency was 100% for osteochondromas induced by conditional inactivation of exostoses (multiple) 1 (Ext1) in chondrocytes, osteosarcomas induced by tibial intramedullary inoculation of Moloney murine sarcoma virus, and osteosarcomas induced by conditional inactivation of Trp53-with or without inactivation of Rb1-in osteoblast precursors. Spontaneous osteogenic neoplasms were more frequent than spontaneous cartilaginous and vascular types. Malignant neoplasms were more frequent than benign ones. The age of occurrence for spontaneous neoplasms ranged from 37 to 720 days (M = 316.35) for benign neoplasms and 35 to 990 (M = 299.28) days for malignant. In genetically engineered mice, the average age of occurrence ranged from 28 to 70 days for benign and from 35 to 690 days for malignant. Histologically, nonosteogenic neoplasms were similar across strains and mutant stocks; osteogenic neoplasms exhibited greater diversity. This comparison and summarization of mouse bone neoplasms provides valuable information for the selection of strains to create, compare, and validate models of bone neoplasms.