A method for detecting nucleic acids by (a) providing a sample having target nucleic acids, each nucleic acid having contiguous first, second, and third domains; (b) contacting the sample with probe sets to form hybridization complexes, wherein each probe set includes (i) a first probe having a sequence that is complementary to the first domain; and (ii) a second probe having a sequence substantially complementary to the third domain; (c) extending the first probes along the second domains of the complexes while the complexes are immobilized on a solid support; (d) ligating the extended first probes to the second probes to form templates; (e) amplifying the templates with primers that are complementary to the first and second priming sequences to produce amplicons; and (f) detecting the amplicons on the surface of a nucleic acid array.