A multilayer wiring board 10 comprises a substrate having a plurality of layers of reinforced resin material 12,18,19,26,18′,19′,26′, a patterned conductive layer 28,28′ provided on at least one major surface of the substrate, a plurality of via holes 30,32,34,36 provided at least partly through the substrate, and a plurality of signal carrying wires 20,20′. The signal carrying wires 20,20′ are provided between at least two of the layers of reinforced resin material 12,18,19,26,18′,19′,26′. The signal carrying wires 20,20′ can be embedded in a resin layer 21,21′, and the resin layer 21,21′ sandwiched between a pair 18,19,18′,19 of the layers of reinforced resin material. The reinforced resin material 12,18,19,26,18′,19 is preferably a fiber reinforced resin material, such as a glass fiber reinforced epoxy or polyimide material. In some applications, a constrained core 22,24,22′,24′, e.g., a copper/ molybdenum/copper laminate, can be provided between a major surface of the substrate and the pair 18,19,18′,19 of reinforced resin layers sandwiching the signal carrying wires 20,20′. The board 10 can be used in a multilayer wiring package wherein a plurality of integrated circuit chips are mounted on a major surface of the board 10. Applications include digital, high-speed digital and RF interconnects.