  We elucidate the structural transitions in a helical off-lattice homopolymer
induced by crowding agents, as function of the number of monomers ($N$) and
volume fraction ($\phi_c$) of crowding particles. At $\phi_c = 0$, the
homopolymer undergoes transitions from a random coil to a helix, helical
hairpin \textbf{HH}, and helix bundle \textbf{HB} structures depending on $N$,
and temperature. Crowding induces chain compaction that can promote \textbf{HH}
or \textbf{HB} formation depending on $\phi_c$. Typically, the helical content
decreases which is reflected in the decrease in the transition temperatures
that depend on $\phi_c$, $N$, and the size of the crowding particles.
