There are lessons to be learned from more than 40 years of oil and gas production history of the Monterey Formation in offshore California. From the exploratory to the development phase, there are considerations in applying interpretation processes developed for conventional reservoirs. These include issues about the use of conventional wireline data for reservoir characterization, formation damage, formation testing and interpretation of DST’s and well tests. But the most interesting observations are related to performance based reservoir characterization. Initial individual well productivities relate to geological composition and state of diagenesis of the formation and associated fracture density depicted from cores, FMI and other fracture identification logs. Presence of reservoir compartments is evident from the performance of nearby wells. Duration of fracture controlled production, cumulative oil production for individual wells and monitoring of water invasion from bottom aquifer are direct indications of compartments sharing a common aquifer. Performance data and other Information from a number separate offshore fields producing from the Monterey Formations are included to demonstrate some of the above concepts.