The Lanceolated Monklet (Micromonacha lanceolata) is a puffbird (Bucconidae) generally considered rare throughout its range. This species is little-studied and its reproductive behavior is largely unknown. Here, we provide the first detailed account of its nesting biology. All 17 nests consisted of round tunnels in earthen banks terminating in widened brood chambers. Tunnels averaged 405.41 ± 59.52 mm in length (n = 14) and 68.64 ± 13.12 by 57.89 ± 12.20 mm (n =16) in diameter at the entrances. The clutch size was two. The unmarked, white eggs averaged 22.53 ± 1.04 by 18.29 ± 0.71 mm (n = 22) and weighed 3.84 ± 0.39 g (n = 19). The incubation period, determined from one nest was 25 days. The number of trips made from three nests averaged 3.42 ± 1.12 per day (n = 33), with each absence lasting an average of 70.54 ± 89.98 mins (n = 113). Nest attentiveness steadily increased from 11.55 to 71.73% and on-bouts from these three nests averaged 166.28 ± 96.58 mins (n = 79). During the nestling period, which we determined from one nest to span 22–23 days, food deliveries consisted of large insects and larvae; averaged over four nests, attendants made 1.72 ± 0.78 (n = 28 days) deliveries per hour.