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H. Hasan (NASA HQ \& STScI), D. Pfenniger (Geneva Obs.), C. A. Norman (JHU \& STScI)
We examine a variety of mechanisms that have been proposed in recent literature as contributors to bulge building in galaxies with a view to understand the constraints within which each mechanism works, the degree to which it contributes to the secular evolution of galaxies, and the observational signatures it would produce. The effects studied include the role of the inner Lindblad resonance (ILR) in orbital instability caused by a central mass concentration in the form of a sphere, a secondary bar, or a ring in a barred galaxy; timescales involved in the bar dissolution process; chaotic mixing processes and cycling. Observational evidence is sought by relating theoretical predictions to observational data on the age of bulges and disks, gas distribution within galaxies, and complex structures seen in central regions of galaxies. In summary, we present an analysis of possible selection effects that affect bulge building, and identify areas where more observational evidence and theoretical analysis is required.