Črnomelj's bus stop is on Trg Svobode. Bus connections are lousy and as they're tailored towards students and workers, the services they do have are mostly in the early morning hours. There is a handful of departures to local villages and Kolpa Valley destinations. Services include:
Ljubljana (€9.20, two hours, 100km) Two daily.
Metlika (€2.30, 30 minutes, 15km) Seven on weekdays, two daily on weekends.
Novo Mesto (€5.20, 70 minutes, 44km) Two daily.
The train station is about 1.5km north of the old town, on Železničarska cesta.
Ljubljana (€7.70, two to 2½ hours, 107km) ten trains daily on weekdays, two to five daily on weekends. All these trains go via Novo Mesto (€3.45, 40 to 50 minutes, 32km).
Metlika (€1.85, 18 minutes, 15km) Heading in the other direction, there are nine services daily on weekdays, and two to five daily on weekends.