A method of forming a three-dimensional object comprising the steps of: a) forming a layer of a particulate composition, the particulate composition comprising a plurality of first particles that comprise: i) a resin component comprising a first resin, the first resin comprising a first resin polymerizable group, the first resin polymerizable group comprising a carbon-carbon double bond directly attached to an electron withdrawing group, ii) a thermal radical initiator dispersed or dissolved in the resin component, and iii) a retardant dispersed or dissolved in the resin component; b) selectively depositing a liquid composition onto the layer of the particulate composition in accordance with computer data corresponding to the shape of at least a portion of a three-dimensional object, the liquid composition comprising: i) a first liquid polymerizable component, the first liquid polymerizable component comprising a first liquid polymerizable group, the first liquid polymerizable group comprising a carbon-carbon double bond that is able to (co)polymerize with the first resin polymerizable group; c) optionally applying electromagnetic radiation to a plurality of the locations of the layer of the particulate composition where the liquid composition has been selectively deposited; d) activating the thermal radical initiator in a plurality of the locations of the layer of the particulate composition where the liquid composition has been selectively deposited; and e) repeating steps a)-d) a plurality of times to form a three-dimensional object. a) forming a layer of a particulate composition, the particulate composition comprising a plurality of first particles that comprise: i) a resin component comprising a first resin, the first resin comprising a first resin polymerizable group, the first resin polymerizable group comprising a carbon-carbon double bond directly attached to an electron withdrawing group, ii) a thermal radical initiator dispersed or dissolved in the resin component, and iii) a retardant dispersed or dissolved in the resin component; i) a resin component comprising a first resin, the first resin comprising a first resin polymerizable group, the first resin polymerizable group comprising a carbon-carbon double bond directly attached to an electron withdrawing group, ii) a thermal radical initiator dispersed or dissolved in the resin component, and iii) a retardant dispersed or dissolved in the resin component; b) selectively depositing a liquid composition onto the layer of the particulate composition in accordance with computer data corresponding to the shape of at least a portion of a three-dimensional object, the liquid composition comprising: i) a first liquid polymerizable component, the first liquid polymerizable component comprising a first liquid polymerizable group, the first liquid polymerizable group comprising a carbon-carbon double bond that is able to (co)polymerize with the first resin polymerizable group; i) a first liquid polymerizable component, the first liquid polymerizable component comprising a first liquid polymerizable group, the first liquid polymerizable group comprising a carbon-carbon double bond that is able to (co)polymerize with the first resin polymerizable group; c) optionally applying electromagnetic radiation to a plurality of the locations of the layer of the particulate composition where the liquid composition has been selectively deposited; d) activating the thermal radical initiator in a plurality of the locations of the layer of the particulate composition where the liquid composition has been selectively deposited; and e) repeating steps a)-d) a plurality of times to form a three-dimensional object. <EOS>