A method of delivering content from a source to a plurality of destinations (816, 818) in a content delivery network, the method comprising: receiving a request for delivery of a piece of content to each of the plurality of destinations, said content comprising one or more portions; receiving information relating to a capability of the destinations, wherein said capability comprises the buffer capacity of the destinations; characterised in that the method further comprises determining when to trigger delivery of the content in a multiple multicast time-shifted content delivery mode based on the received information, the mode comprising delivering the piece of content using a plurality of multicast streams, the plurality of multicast streams each delivering the content with a relative time-shift between corresponding portions of the content in each of the multicast streams; determining a time interval for the relative time-shift between the multicast streams so that the majority of the destinations can buffer the content for that time interval; then triggering delivery of the content in a multiple multicast time-shifted content delivery mode using the determined time interval; wherein, for each trigger, the determination of when to trigger is further based on at least one of: a measure of the number of requests for the content in a preceding time period; a model of predicted requests for the content in a subsequent time period; a determination of the geographical or topological distribution of the existing or expected destinations in the network; the topological or geographical position of the requesting destination in the content delivery network compared to the position of other destinations already receiving the content; and a measure of the network capacity or availability between the source and the plurality of destinations. receiving a request for delivery of a piece of content to each of the plurality of destinations, said content comprising one or more portions; receiving information relating to a capability of the destinations, wherein said capability comprises the buffer capacity of the destinations; characterised in that the method further comprises determining when to trigger delivery of the content in a multiple multicast time-shifted content delivery mode based on the received information, the mode comprising delivering the piece of content using a plurality of multicast streams, the plurality of multicast streams each delivering the content with a relative time-shift between corresponding portions of the content in each of the multicast streams; determining a time interval for the relative time-shift between the multicast streams so that the majority of the destinations can buffer the content for that time interval; then triggering delivery of the content in a multiple multicast time-shifted content delivery mode using the determined time interval; wherein, for each trigger, the determination of when to trigger is further based on at least one of: a measure of the number of requests for the content in a preceding time period; a model of predicted requests for the content in a subsequent time period; a determination of the geographical or topological distribution of the existing or expected destinations in the network; the topological or geographical position of the requesting destination in the content delivery network compared to the position of other destinations already receiving the content; and a measure of the network capacity or availability between the source and the plurality of destinations. a measure of the number of requests for the content in a preceding time period; a model of predicted requests for the content in a subsequent time period; a determination of the geographical or topological distribution of the existing or expected destinations in the network; the topological or geographical position of the requesting destination in the content delivery network compared to the position of other destinations already receiving the content; and a measure of the network capacity or availability between the source and the plurality of destinations.