ZnxCd1-xS single-crystal nanoribbons of controlled composition (where 0 <= x <= 1) can be synthesized by combining laser ablation with thermal evaporation. The nanoribbons (see Figure) exhibit lasing emission that can be continuously tuned within the ranges of 340-390 nm and 485-515 nm. These results suggest that ZnxCd1-xS nanoribbon lasers of pre-selected "tunable" wavelengths between 340 and 515 nm may be achievable by tailoring the value of x.