Technical Abstract: The Southern cattle tick, Boophilus microplus, causes annual economic losses in the hundreds of millions of dollars to cattle producers throughout the world, and ranks as the most economically important tick from a global perspective. Control failures attributable to the development of pesticide resistance have become commonplace and novel control technologies are needed. The availability of the genome sequence will facilitate the development of these new technologies and we are proposing sequencing to a 4-6X draft coverage. Several existing biological resources are available to facilitate a genome sequencing project, including several inbred laboratory tick strains, a database of approximately 45,000 ESTs compiled into a B. microplus Gene Index, a BAC library, an established B. microplus cell line, and genomic DNA suitable for library synthesis. Collaborative projects are underway to map BACs and cDNAs to specific chromosomes and to sequence selected BAC clones. When completed, the genome sequences from the cow, B. microplus and the B. microplus-borne pathogens, Babesia bovis and Anaplasma marginale, will enhance studies of host-vector-pathogen systems. Genes involved in the regeneration of amputated tick limbs and transitions through developmental stages are largely unknown. Studies of these and other interesting biological questions will be advanced by tick genome sequence data. Comparative genomics offers the prospect of new insight into many, perhaps all, aspects of the biology of ticks and the pathogens they transmit to farm animals and people. The B. microplus genome sequence will fill a major gap in comparative genomics: a sequence from the metastriata lineage of ticks.