Compositions and methods for inhibiting the actions of non-coding RNAs such as miRNAs and piRNAs are provided. The compositions comprise single or double stranded oligonucleotides conjugated with Minor Groove Binders (“MGBs”). The oligonucleotides can vary in length, can contain nucleotides having one or more modifications, and have regions that are substantially complementary to one or more mature miRNAs or piRNAs.