The most recent measurements leading to improved Li I energy levels appeared in the late 1950s. Since then, many highand ultrahigh-precision spectroscopy techniques have been used to measure the fine and hyperfine structures and isotope shifts of this atom. Most previous measurements were made on Li. Using highand low-current hollow cathode sources and Fourier-transform spectrometry, we have made measurements in both Li and Li including nine previously unmeasured infrared lines. Wave-number measurements were obtained on 34 lines from 1829 to 30 925 cm '. The strongest lines have been determined to~0.0010 crn '. We also measured 22 new isotope shifts, and added specific mass shifts for five levels. The resonance lines at 6707 A in both isotopes, emitted by low-current, commercial lithium hollow cathode sources, were measured tõ 0.0005 cm '. The energy levels have been recalculated using the new data. PACS number(s): 32.30.Jc