The present paper is concerned with aspects of the semantics of the participial construction in English. The argument developed is based on the assumption that the grammatical form is not semantically arbitrary, with its varied uses having a conceptual core running through them. The paper argues that the temporal relationship of simultaneity plays a crucial role in motivating the usage of the construction. The various ways the basic notion is interpreted or extended are shown to combine to produce a coherent semantic picture of a grammatical form known for its markedly diverse use.