This paper describes morphometric relationships, and the timing of gametogenic development and spawning for the geoduck clam Panopea globosa (Dall 1898) from a population in the east central Gulf of California. Clams were collected monthly for a year (October 2004 to October 2005), and were measured and weighed to obtain morphometric relationships. Standard histological analysis and measurements of oocyte diameters were used to describe the timing of gametogenic development and spawning. Most morphometric variables were significantly correlated, however the coefficients of determination were generally low (<0.5) indicating high variation in measured traits. Early gametogenic development was observed in late summer/autumn when SST was high (∼30°C). Development increased as water temperatures fell with ripe individuals observed in early winter (∼20°C). Spawning occurred between January and February (winter), when SST were at their coolest (∼18°C). Cytological characteristics of the gonad and averages of oocyte diameters for the different reproductive phases were similar to other geoduck species previously described. Overall sex ratios were equal. This study is the first ecological study to be conducted for P. globosa. Given the development of fisheries for P. globosa and the interest in developing aquaculture for this species, the data provide valuable information for fisheries managers and aquaculturalists and represent the basis for further research on this species.