Abstract: The invention concerns polynucleotide compositions and methods for copying and amplifying mRNA, and provides for a method of making a linear cDNA or cRNA library based on original mRNA templates. The linear polynucleotides have the advantage of being more completely representative of full length mRNA transcripts than previously possible, and the linear libraries constructed by these methods represent relative abundances of the original transcripts in the original population of mRNA more accurately than previously possible.