In this issue, McDonald et al. describe the itinerary of the incoming human immunodeficiency virus (HIV) during its travels to the host nucleus. They show that subviral particles tagged with the green fluorescent protein (GFP) are propelled along microtubules (MTs) by minus-end-directed and presumably plus-end-directed MT motors. The tracked particles correspond to functional units, since they no longer include a viral envelope, but do include viral matrix protein, Vpr, capsid protein, and reverse transcription activity.