The Global Digital Seismograph Network (GDSN), which consists of the Seismic Research Observatories, the Abbreviated Seismic Research Observatories, and the Digital World-Wide Standardized Seismograph Network stations, and the International Deployment Accelerometers (IDA) network, which is operated by the University of California, produce digital seismic data in overlapping bands from short to tidal periods. GDSN and IDA data are available through national and regional data centers, the GDSN data on network-day tapes and the IDA data on bimonthly network tapes. The digital waveforms are being used in research applications that benefit from the high resolution and wide dynamic range of the data, and the ease and speed with which large volumes of digital data can be processed. The usefulness of the data is being enhanced by special processing techniques that overcome some of the constraints of band-limited recording. GDSN improvements under study include an increase in short-period bandwidth, addition of horizontal short-period recording, and the recording of very long-period signals at SRO stations. Several additional stations with borehole seismometers are planned, possibly with satellite data telemetry to the United States. However, in the future, the most likely source of new GDSN data is through the acquisition of digital data from independently operated national and regional networks that are being installed or contemplated in several countries, including the United States.