In general, lion tamarins were relatively slow to become comfortable with train­ ing. Building a rapport with each individual animal was a lengthy process, and relatively long training sessions were needed. On the contrary, tamarins (,Saguinus spp .) responded more quickly than all marmosets and cebids with re­ gard to approaching trainers as well as learning behaviors. Individuals would be­ come engaged immediately as the trainer entered the enclosure and set up materials, volunteering to begin the training session. However, Saguinus spp. lost interest in sessions more rapidly than did marmosets or cebids. Shorter, more frequent sessions throughout the day proved most productive for Saguinus spp. Pied tamarins stopped responding to the trainer after just a few minutes into the sessions. However, if the trainer left the enclosure and then re-entered a short time (even < 1 min) later, they generally regained interest. Thus, a sched­ ule that provided up to 10 short training sets a day was the most productive for this species.