Here we apply high throughput short-read sequencing of poly-A selected RNA to capture the metatranscriptome of an estuarine dinoflagellate bloom.This environmental sample provides a high fidelity metatranscriptomic snapshot of a harmful algal bloom. The taxonomic composition of the bloom community is dominated by Prorocentrum minimum but also includes several dinoflagellates, ciliates, animals, and fungi. The assembled metatranscriptome reveals the functional genomic composition of a metabolically active community. For comparative purposes we also generated a transcriptome of a clonal isolate of the Prorocentrum minimum.