1. Introduction – 3 – Multi-wavelength observations of nearby star-forming regions have shown that the vast majority of pre-main-sequence (PMS) stars are either accreting Classical T Tauri Stars (CTTSs) with excess emission extending all the way from the near-IR to the millimeter or, more evolved, non-accreting, Weak-line T Tauri Stars (WTTSs) with bare stellar photospheres. The fact that very few objects lacking near-IR excess show mid-IR or (sub)millimeter excess emission implies that, once the inner disk dissipates, the entire primordial disk disappears very rapidly (Wolk & Walter 1996; Andrews & Williams 2005,2007; Cieza et al. 2007). The few objects that are caught in the short transition between typical CTTSs and disk-less WTTSs usually have optically thin or non-existent inner disks and optically thick outer disks (i.e., they have reduced opacity in the inner regions of the disk). The reduced opacity in the inner disk is the defining characteristic of the so called transition disks. The precise definitions of what constitutes a transition object found in the disk evolution literature are, however, far from homogeneous (see Evans et al. 2009 for a detailed description of the transition disk nomenclature). Transition disks have been defined as objects with no detectable near-IR excess, steep slopes in the mid-IR, and large far-IR excesses (e.g., Muzerolle et al. 2006, Sicilia-Aguilar et al. 2006a) This definition has been relaxed by some authors (e.g., Brown et al. 2007, Cieza et al. 2008) to include objects with small, but still detectable, near-IR excesses. Transition disks have also been more broadly defined in terms of a significant decrement relative to the Taurus median Spectral Energy Distribution (SED) at any or all wavelengths (e.g., Najita et al. 2007). This broad definition is the closest one to the criteria we adopt to select our sample (see § 2). Even though, according to our definition, many transition disks have inner disks with non-zero opacity, we refer to their regions of low opacity as the “inner opacity hole.”