Integrated Ocean Drilling Program (IODP) expedition 344 was implemented from October 23 to December 11, 2012 in the offshore Costa Rica, which is known for the frequent occurrence of earthquakes. This expedition is part of the Costa Rica Seismogenesis Program (CRISP) that has an overarching goal of elucidating the origin, nucleation, and propagation of earthquakes in an erosive convergent margin. We participated in this expedition. Here we present numerous aspects of this expedition in this paper including tectonic settings of the drilling area, major scientific goals, field operation, preliminary results of this expedition, and post-cruise activities. More detailed and much in-depth research is  carried out after the cruise and post cruise results will be reported in the meeting to be held in Nanjing University in 2014. The synthesis of these new results should lead to better understanding of the seismogenesis of the study area.