This study had three purposes: first, explore any common phenomenon of secondary mathematics teachers’ experience in secondary mathematics professional development (MPD); second, determine if there were positive changes in teacher attitudes after completing secondary MPD; and finally, if a positive change in teacher attitude was identified, describe the shared experiences in secondary MPD to in a way that cannot be revealed through ordinary observations. It was the intent of this study to identify positive changes in teacher attitudes not to measure their magnitude. This study implemented a mixed methods design using descriptive statistics and categorical analysis on data from pre- and post-surveys to search for any positive change in teacher attitudes and data analysis from in-depth interviews of participants of a MPD experience. The study had two research questions. The first research question was, “Can teachers with initially poor attitudes about MPD gain positive attitudes in one or more of the four areas of MPD through mandated participation in MPD?” The second was, “If a change in teacher attitude is identified, can phenomena associated with that change be categorized within one or more of the four areas of MPD?” Three instruments were used: electronic versions of the Local Systematic Change Through Teacher Enhancement Mathematics 6-12 Survey referred to as Survey 1 and a self-report survey referred to as Survey 2, as well as multiple in-depth interviews of select participants of a common MPD. Analysis of data from Survey 1 identified eight participants as possible candidates to participate in the interview process of which six were supported by data from Survey 2. Four of the six candidates accepted an invitation to participate in two in-depth interviews each. There was evidence that teachers with initially poor attitudes about MPD can gain positive attitudes in one or more of the four domains of MPD after participating in mandated MPD. However, the answer to the second research question remained unanswered because results from data analysis were inconclusive. Three recurring themes surfaced from the interviews: (a) the need for explicit learning targets, (b) need for professional treatment of participants, and (c) obstacles to the four domains of MPD.