In order to efficiently utilize the limited transmission bandwidth of a communications network, e.g., a cable network, guide data for constructing an interactive program guide (IPG) is delivered to a set-top terminal using different methodologies. For example, the guide data associated with those programs which are likely of interest to a user is automatically provided piecemeal in a broadcast stream. The set-top terminal, along with other terminals, may retrieve from such a broadcast stream some or all of the guide data therein over time, which is cached in the terminal in anticipation of a user's invocation of an IPG. On the other hand, the guide data associated with those programs which are less likely of interest to a user is furnished upon request by the set-top terminal needing such guide data to realize an IPG desired by the user. In addition, guide data for each program may be divided into detail guide data providing details of the program (e.g., a synopsis of the program content), and grid guide data providing basic information about the program (e.g., title, channel and broadcast time). A first time window and a second time window may be defined such that the grid guide data associated with those programs broadcast within the first time window and the detail guide data associated with those programs broadcast within the second time window are automatically provided in the broadcast stream. The rest of the detail and grid guide data may be furnished upon request when needed.