Interactive systems, in existence for nearly 15 years, are becoming increasingly important, both for information retrieval and library support operations. The virtues of these systems are speed, intimacy, and—if time‐sharing is involved—economy. The major problems are the cost of the large computers and files necessary for bibliographic data, the still‐high cost of communications, and the generally poor design of the user‐system interfaces. The desirable features of online retrieval interfaces are only now being defined and tested in a systematic way, e.g., by the National Library of Medicine in its AIM‐TWX nationwide experimental retrieval service. System implementers must, in addition to engineering the right capabilities into online systems, also make a careful, concerted effort to engineer user acceptance. Common pitfalls here include overselling system capabilities and failure to take into account the social context around the user terminal. The major national problem is to avoid or limit wasteful and expensive duplication in providing nationwide search access to the hundreds of public and private data bases that will be readily available during the next few years. We do not need technological breakthroughs to exploit the potential of online systems, but we do need breakthroughs in organizing for technological change.