A lighted nock system includes a lighted nock assembly and a plurality of adaptors. The lighted nock assembly includes a shaft insertion portion having a shaft outer shape and shaft outer dimension. The first adaptor includes an internal opening having an internal size and internal shape configured to mate with the shaft insertion portion of the lighted nock assembly. The second adaptor includes the same internal opening size and shape as the first adaptor. The outer diameter of the second adaptor is different than the outer diameter of the first adaptor. A plurality of adaptors having different sized outer diameters, but the same internal configurations, can be provided in a single package with the lighted nock assembly. The lighted nock assembly can include a rotatable lockout collar to prevent unintended activation of the lighted nock assembly.