Research has documented 237 distinct reasons for engaging in sex, which have been clustered into the 141-item, 13 subscale YSEX? instrument. Although the YSEX? has impressive psychometric properties, the required completion time is a barrier to its use in time-constrained contexts. The current studies develop and validate a short-form version of the instrument. The new 28-item, 14 subscale YSEX?-SF demonstrates acceptable model fit and good internal-reliability, with evidence for cross-form and construct validity. The YSEX?-SF maintains the original instrument's sound psychometric properties with a significantly shorter completion time, which may facilitate the study of sexual motivation.